Work through the levels in order. Type your answer and press Check — open the worked solution if you get stuck. Answers like -6, 3/4 or 0.25 are typed exactly as shown.
Level 1 · Warm-up
1 A triangle has angles 40° and 75°. Find the third. (degrees)
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65°.
2 What do the angles of a quadrilateral add to? (degrees)
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360°.
3 What is each angle of an equilateral triangle? (degrees)
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60°.
Level 2 · Core
4 A triangle has angles 55° and 65°. Find the third. (degrees)
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60°.
5 A quadrilateral has angles 70°, 110° and 95°. Find the fourth. (degrees)
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85°.
6 An isosceles triangle has an apex angle of 80°. Find each base angle. (degrees)
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100 ÷ 2 = 50°.
Level 3 · Challenge
7 An isosceles triangle has an apex angle of 40°. Find each base angle. (degrees)
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140 ÷ 2 = 70°.
8 A triangle has interior angles 70° and 50°. Find the exterior angle opposite them. (degrees)
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70 + 50 = 120°.
9 An isosceles triangle has base angles of 55° each. Find the apex angle. (degrees)
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180 − 110 = 70°.