Every angles question from 25 Cambridge IGCSE Mathematics (0580) past papers (May/June 2025 to May/June 2026), syllabus section 4.6. 34 questions covering Core and Extended tiers, ordered from Core to Extended. Each question is labelled with its question paper code (for example 0580/11/M/J/26) and every final answer matches the official Cambridge mark scheme. Try each question first, then click “Show solution” to check your working. This page is part of our IGCSE Maths 0580 Geometry past paper questions.
0580 Angles past paper questions: Core (Papers 1 and 3)
May/June 2026 · Paper 1 · 0580/11/M/J/26 · Q10
The diagram shows two straight lines intersecting two parallel lines.
Complete each statement with the correct geometrical reason: x = 67 because …; y = 81 because …
Show solution
- x and the 67° angle are between the parallel lines on opposite sides of the crossing line (a Z-shape).
- x = 67 because alternate angles are equal
- y and the 81° angle are in the same position at each parallel line (an F-shape).
- y = 81 because corresponding angles are equal
- Tip: Write the full reason. “Z-angles” or “F-angles” on their own do not score.
May/June 2026 · Paper 1 · 0580/12/M/J/26 · Q17
(a) Two of the angles in a triangle are 100° and 30°. Work out the size of the third angle.
(b) Work out the size of an interior angle of a regular 10-sided polygon.
Show solution
- The angles in a triangle add up to 180°.
- Third angle = 180 − 100 − 30 = 50°
- The exterior angles of any polygon add up to 360°. A regular 10-sided polygon has 10 equal exterior angles.
- Exterior angle = 360 ÷ 10 = 36°.
- Interior angle and exterior angle make a straight line, so interior angle = 180 − 36 = 144°
May/June 2026 · Paper 3 · 0580/31/M/J/26 · Q23
Calculate the interior angle of a regular pentagon.
Show solution
- The exterior angles of a polygon add up to 360°. A regular pentagon has 5 equal exterior angles.
- Exterior angle = 360 ÷ 5 = 72°.
- Interior angle = 180 − 72 = 108°
May/June 2026 · Paper 3 · 0580/33/M/J/26 · Q19
Calculate the interior angle of a regular polygon with 12 sides.
Show solution
- The exterior angles of any polygon add up to 360°. A regular 12-sided polygon has 12 equal exterior angles.
- Exterior angle = 360 ÷ 12 = 30°.
- Interior and exterior angles make a straight line, so interior angle = 180 − 30 = 150°
Feb/Mar 2026 · Paper 1 · 0580/12/F/M/26 · Q10
The diagram shows a triangle on a straight line, with a second line parallel to the left side of the triangle. The angles 60° and 65° are marked at the right-hand vertex. Work out the values of a, b and c.
Show solution
- The two sloping lines are parallel. a is at the top vertex and the 60° angle is at the right-hand vertex, between the parallel lines (a Z-shape).
- a = 60 because alternate angles are equal.
- b is at the left-hand vertex in the same position as the 65° angle is at the right-hand vertex (an F-shape).
- b = 65 because corresponding angles are equal.
- c, 60° and 65° lie together on the straight line, and angles on a straight line add up to 180°.
- c = 180 − 60 − 65, so c = 55
Oct/Nov 2025 · Paper 1 · 0580/11/O/N/25 · Q15
ABC is a straight line and ABD is an isosceles triangle with DA = DB. Angle DBC = 140° and angle ADB = x°. Work out the value of x.
Show solution
- ABC is a straight line, so angles on it add up to 180°: angle ABD = 180 − 140 = 40°.
- DA = DB, so the triangle is isosceles and the base angles are equal: angle DAB = 40°.
- Angles in a triangle add up to 180°: x = 180 − 40 − 40 = 100
Oct/Nov 2025 · Paper 1 · 0580/12/O/N/25 · Q12
The diagram shows a parallelogram with two adjacent angles (3x + 10)° and (x − 30)°.
(a) Write an equation and solve it to find the value of x. (b) Find the value of the largest angle in this parallelogram.
Show solution
- Next-door (adjacent) angles in a parallelogram add up to 180°, because the sides are parallel.
- 3x + 10 + x − 30 = 180
- Collect like terms: 4x − 20 = 180.
- Add 20 to both sides: 4x = 200.
- Divide by 4: x = 50
- Substitute x = 50 into each angle: 3 × 50 + 10 = 160° and 50 − 30 = 20°.
- Check: 160 + 20 = 180 ✓
- The largest angle is 160°
Oct/Nov 2025 · Paper 1 · 0580/12/O/N/25 · Q14
Triangle DEF has its vertices on the sides of triangle ABC, with D on AB, E on AC and F on BC. Angle ABC = 50°, angle BFD = 45°, angle EFC = 35°, angle ADE = 25° and angle DEF = x°.
Find the value of x.
Show solution
- Work round the shape one triangle or line at a time.
- Triangle BDF: angle BDF = 180 − 50 − 45 = 85° (angles in a triangle add up to 180°).
- D is on the straight line ADB, so angle FDE = 180 − 85 − 25 = 70° (angles on a straight line).
- F is on the straight line BFC, so angle DFE = 180 − 45 − 35 = 100°.
- Triangle DEF: x = 180 − 70 − 100 = 10
Oct/Nov 2025 · Paper 1 · 0580/12/O/N/25 · Q22
Work out the size of one interior angle of a regular hexagon.
Show solution
- The exterior angles of any polygon add up to 360°. A regular hexagon has 6 equal exterior angles.
- Exterior angle = 360 ÷ 6 = 60°.
- Interior angle = 180 − 60 = 120°
Oct/Nov 2025 · Paper 1 · 0580/13/O/N/25 · Q3
(a) Measure angle a. (b) Write down the mathematical name of this type of angle.
Show solution
- Put the centre of the protractor on the corner of the angle, with 0° along one arm.
- Read the scale where the other arm crosses it. Use the scale that starts at 0 on your first arm.
- Angle a = 123°
- The angle is between 90° and 180°.
- It is obtuse
Oct/Nov 2025 · Paper 1 · 0580/13/O/N/25 · Q10
The diagram shows an isosceles triangle with a 40° angle at its top vertex, between a pair of parallel lines. Its base angles are x° and the angle y° is on a straight line next to one of them.
(a) Find the value of x. (b) Find the value of y. Give a geometrical reason for your answer.
Show solution
- The angles in a triangle add up to 180°, so the two base angles together are 180 − 40 = 140°.
- The triangle is isosceles, so the base angles are equal: x = 140 ÷ 2 = 70
- y and x lie together on a straight line.
- y = 180 − 70, so y = 110 because angles on a straight line add up to 180°
Oct/Nov 2025 · Paper 1 · 0580/13/O/N/25 · Q19
Find the number of sides of a regular polygon with interior angle 160°.
Show solution
- An interior angle and an exterior angle make a straight line, so exterior angle = 180 − 160 = 20°.
- The exterior angles of a polygon add up to 360°.
- Number of sides = 360 ÷ 20 = 18
Oct/Nov 2025 · Paper 3 · 0580/31/O/N/25 · Q9
(a) Write down the mathematical name for the type of angle shown (more than 180°).
(b) Triangle ABC has angle A = 54° and angle C = 102°. Lily says angle B, x, is 34. Give a geometrical reason why Lily is not correct.
(c) ABCD is a quadrilateral with angle A = 48°, angle B = 75° and angle D = 126°. DCE is a straight line. Calculate x, the angle BCE.
Show solution
- An angle bigger than 180° (but less than 360°) is a reflex angle.
- Add Lily’s angle to the other two: 54 + 102 + 34 = 190°.
- The total should be exactly 180°, because Angles in a triangle add up to 180°
- So Lily is wrong. The correct value is x = 180 − 54 − 102 = 24.
- The angles in a quadrilateral add up to 360°.
- Angle BCD = 360 − 48 − 75 − 126 = 111°.
- D, C and E lie on a straight line, so x and angle BCD add up to 180°.
- x = 180 − 111 = 69
Oct/Nov 2025 · Paper 3 · 0580/31/O/N/25 · Q20(a)
Work out the size of one interior angle of a regular 8-sided polygon.
Show solution
- The exterior angles of a polygon add up to 360°. A regular 8-sided polygon has 8 equal exterior angles.
- Exterior angle = 360 ÷ 8 = 45°.
- Interior angle = 180 − 45 = 135°
Oct/Nov 2025 · Paper 3 · 0580/33/O/N/25 · Q15
Three straight lines meet in the diagram, with angles 68°, 43°, 135° and x° around a point. Find the value of x.
Show solution
- The four angles go all the way round one point.
- Angles at a point add up to 360°.
- x = 360 − 68 − 43 − 135 = 114
May/June 2025 · Paper 1 · 0580/11/M/J/25 · Q18
The diagram shows two straight lines intersecting two parallel lines. Angles of 110° and 50° are marked at the lower parallel line.
(a) Find the value of x. Give a geometrical reason for your answer.
(b) Find the value of y. Give a geometrical reason for your answer.
(c) Find the value of z.
Show solution
- x and the 50° angle are on opposite sides of a line that crosses the parallel lines, between them (a Z-shape).
- x = 50, because alternate angles are equal
- y is in the same position at the top parallel line as the 110° angle is at the bottom one (an F-shape).
- y = 110, because corresponding angles are equal
- z is the third angle of the triangle made by the two straight lines and the lower parallel line.
- The angle inside the triangle next to the 110° angle is 180 − 110 = 70° (angles on a straight line).
- Angles in a triangle add up to 180°: z = 180 − 70 − 50 = 60
May/June 2025 · Paper 1 · 0580/13/M/J/25 · Q4
The diagram shows a quadrilateral with sides of equal length. Two neighbouring angles are a° and 2a°.
(a) Write down the mathematical name for this quadrilateral.
(b) Work out the value of a.
Show solution
- All four sides are equal, but the angles are not right angles, so it is not a square.
- The quadrilateral is a rhombus
- Opposite sides of a rhombus are parallel, so neighbouring angles are co-interior and add up to 180°.
- a + 2a = 180
- 3a = 180, so a = 60
0580 Angles past paper questions: Extended (Papers 2 and 4)
May/June 2026 · Paper 2 · 0580/22/M/J/26 · Q11
Find the number of sides of a regular polygon with interior angle 140°.
Show solution
- An interior angle and an exterior angle make a straight line: exterior angle = 180 − 140 = 40°.
- The exterior angles of any polygon add up to 360°.
- Number of sides = 360 ÷ 40 = 9
May/June 2026 · Paper 2 · 0580/23/M/J/26 · Q11
The interior angle of a regular polygon is 135°. Find the number of sides of this regular polygon.
Show solution
- An interior angle and an exterior angle make a straight line: exterior angle = 180 − 135 = 45°.
- The exterior angles of any polygon add up to 360°.
- Number of sides = 360 ÷ 45 = 8
May/June 2026 · Paper 4 · 0580/42/M/J/26 · Q1
Triangle ABC is isosceles with AB = AC. Angle BAC = 30° and angle ACB = x°. Find the value of x.
Show solution
- AB = AC, so the triangle is isosceles and the base angles at B and C are equal.
- The angles in a triangle add up to 180°, so the two base angles together = 180 − 30 = 150°.
- Each base angle = 150 ÷ 2 = 75°.
- x = 75
May/June 2026 · Paper 4 · 0580/43/M/J/26 · Q8(a)
AB and CD are parallel lines. AD and BC are straight lines that intersect at X. Angle ABX = y°. Complete the statement with a geometrical reason: angle DCX = y° because …
Show solution
- BC is a straight line crossing the two parallel lines AB and CD.
- Angles ABX and DCX are on opposite sides of BC, between the parallel lines (a Z shape).
- Angle DCX = y° because alternate angles are equal
Feb/Mar 2026 · Paper 2 · 0580/22/F/M/26 · Q14
The diagram shows part of a regular polygon ABCDE. Angle ABD = 135° and angle CBD = x°. By finding the value of x, work out the number of sides of this polygon.
Show solution
- In a regular polygon all sides are equal, so BC = CD and triangle BCD is isosceles.
- The base angles of triangle BCD are equal: angle CDB = angle CBD = x°, so angle BCD = 180 − 2x.
- All interior angles are equal, so angle ABC = angle BCD.
- Angle ABC = angle ABD + angle DBC = 135 + x.
- Set up the equation: 135 + x = 180 − 2x, so 3x = 45 and x = 15.
- Interior angle = 135 + 15 = 150°, so exterior angle = 180 − 150 = 30°.
- Number of sides = 360 ÷ 30 = 12
Feb/Mar 2026 · Paper 4 · 0580/42/F/M/26 · Q2
ABC is a triangle with a right angle at A. ADB and DCE are straight lines and angle ADC = 74°. Angle BDC = x° and angle ACE = y°. Find the value of x and the value of y.
Show solution
- ADB is a straight line, so the angles at D on it add up to 180°.
- x = 180 − 74 = 106
- Triangle ADC has a right angle at A. Angles in a triangle add up to 180°.
- Angle ACD = 180 − 90 − 74 = 16°.
- DCE is a straight line, so angle ACE and angle ACD add up to 180°.
- y = 180 − 16 = 164
Oct/Nov 2025 · Paper 2 · 0580/21/O/N/25 · Q2
In the diagram, AC = BC. The angles 148° and 82° are marked at C, round the point with angle ACB. Work out angle CAB.
Show solution
- The angles round the point C add up to 360°: angle ACB = 360 − 148 − 82 = 130°.
- AC = BC, so triangle ABC is isosceles and its base angles CAB and CBA are equal.
- The two base angles together are 180 − 130 = 50°.
- Angle CAB = 50 ÷ 2 = 25°
Oct/Nov 2025 · Paper 2 · 0580/21/O/N/25 · Q3
Find the interior angle of a regular 20-sided polygon.
Show solution
- The exterior angles of a polygon add up to 360°. A regular 20-sided polygon has 20 equal exterior angles.
- Exterior angle = 360 ÷ 20 = 18°.
- Interior angle = 180 − 18 = 162°
Oct/Nov 2025 · Paper 2 · 0580/22/O/N/25 · Q6
ABCD is a quadrilateral. E lies on CD and AE is parallel to BC. EA = ED. Angle BAE = 75° and angle BCD = 80°.
Find (a) angle ABC (b) angle AED (c) angle DAB.
Show solution
- AE is parallel to BC, and AB crosses both lines. Angles BAE and ABC are on the same side, between the parallels (co-interior).
- Co-interior angles add up to 180°: angle ABC = 180 − 75 = 105°
- AE is parallel to BC, and the straight line DC crosses both. Angle AED and angle BCD are in the same position (corresponding).
- Angle AED = 80°
- EA = ED, so triangle AED is isosceles and angle EAD = angle EDA.
- The two equal angles together are 180 − 80 = 100°, so angle EAD = 50°.
- Angle DAB = angle DAE + angle EAB = 50 + 75 = 125°
Oct/Nov 2025 · Paper 2 · 0580/22/O/N/25 · Q16
AB and BD are two sides of a regular 15-sided polygon. AB and BC are two sides of a regular n-sided polygon. Angle DBC = 14°. Work out the value of n.
Show solution
- Regular 15-sided polygon: exterior angle = 360 ÷ 15 = 24°, so interior angle ABD = 180 − 24 = 156°.
- Angle ABC is an interior angle of the n-sided polygon: ABC = ABD + DBC = 156 + 14 = 170°.
- Its exterior angle = 180 − 170 = 10°.
- n = 360 ÷ 10 = 36
Oct/Nov 2025 · Paper 2 · 0580/23/O/N/25 · Q1
The diagram shows an isosceles triangle with base angles of 25° and top angle x°. Find the value of x.
Show solution
- The triangle is isosceles, so both base angles are 25°.
- Angles in a triangle add up to 180°: x = 180 − 25 − 25 = 130
Oct/Nov 2025 · Paper 2 · 0580/23/O/N/25 · Q5
ABCD is a rectangle. EFG is an equilateral triangle that touches the rectangle at F (on BC) and G (on AD). Angle BFE = 12°, angle GFC = x° and angle FGD = y°.
Find the value of x and the value of y.
Show solution
- EFG is equilateral, so each of its angles is 60°. Angle EFG = 60°.
- B, F and C lie on a straight line, so the angles at F along it add up to 180°.
- x = 180 − 12 − 60 = 108
- BC is parallel to AD, and the line FG crosses both. Angles GFC and FGD are co-interior (between the parallels on the same side).
- Co-interior angles add up to 180°: y = 180 − 108 = 72
Oct/Nov 2025 · Paper 4 · 0580/41/O/N/25 · Q3
The diagram shows two parallel lines and a straight line crossing them, with angles 55° and x° marked.
Show solution
- The 55° angle and the angle next to x on the top line are alternate angles (Z-shape between the parallel lines), so that angle is also 55°.
- That angle and x lie on the same straight line, and angles on a straight line add up to 180°.
- x = 180 − 55 = 125
Oct/Nov 2025 · Paper 4 · 0580/43/O/N/25 · Q5
(a) The diagram shows a regular decagon. AB is a line of symmetry through vertex A, and angle d° is half an interior angle at A. Work out the value of d.
(b) The exterior angle of a regular polygon with n sides is 45°. Work out the value of n.
Show solution
- Exterior angle of a regular decagon = 360 ÷ 10 = 36°.
- Interior angle = 180 − 36 = 144°.
- The line of symmetry through A cuts this angle exactly in half: d = 144 ÷ 2 = 72
- The exterior angles of any polygon add up to 360°, and in a regular polygon they are all equal.
- n = 360 ÷ 45 = 8
May/June 2025 · Paper 2 · 0580/21/M/J/25 · Q2
The diagram shows two parallel lines intersecting two straight lines. One straight line is steep and the other is shallow. Angles of 76° and 158° are marked, along with w°, x° and y°. Find the values of w, x and y.
Show solution
- w is in the same position at the upper parallel line as the 158° angle is at the lower one, on the shallow line (an F-shape).
- w = 158 (corresponding angles are equal).
- x is in the same position at the upper parallel line as the 76° angle is at the lower one, on the steep line.
- x = 76 (corresponding angles are equal).
- y is inside the triangle made by the steep line, the shallow line and a parallel line.
- The angle in the triangle next to 158° is 180 − 158 = 22° (angles on a straight line). The angle on the steep line is 76°.
- Angles in a triangle add up to 180°: y = 180 − 76 − 22 = 82.
- w = 158, x = 76, y = 82
May/June 2025 · Paper 2 · 0580/21/M/J/25 · Q5
The interior angle of a regular polygon is 150°. Find the number of sides of this polygon.
Show solution
- An interior angle and an exterior angle make a straight line: exterior angle = 180 − 150 = 30°.
- The exterior angles of any polygon add up to 360°.
- Number of sides = 360 ÷ 30 = 12
May/June 2025 · Paper 2 · 0580/22/M/J/25 · Q3
The diagram shows two straight lines intersecting two parallel lines. Angles of 45° and 65° are marked at the upper parallel line. The two straight lines cross at the lower parallel line, where x° and y° are marked.
Find the value of x and the value of y.
Show solution
- The two straight lines and the upper parallel line make a triangle. Its angles at the upper line are 45° and 65°.
- x is the third angle of that triangle. Angles in a triangle add up to 180°.
- x = 180 − 45 − 65 = 70.
- y is between the lower parallel line and the line that makes 65° with the upper parallel line, on the opposite side (a Z-shape).
- y = 65 because alternate angles are equal.
- x = 70, y = 65
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