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 Two complementary angles: one is 40°. Find the other. (degrees)
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50°.
2 Two supplementary angles: one is 120°. Find the other. (degrees)
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60°.
3 Angles around a point add to how many degrees?
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360°.
Level 2 · Core
4 Two supplementary angles: one is 143°. Find the other. (degrees)
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37°.
5 Angles at a point are 120°, 95° and x. Find x. (degrees)
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360 − 215 = 145°.
6 Two lines cross. One angle is 130°. What is the angle opposite it? (degrees)
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130°.
Level 3 · Challenge
7 Angles on a straight line are 40°, 65° and y. Find y. (degrees)
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75°.
8 Two lines cross. One angle is 130°. What is the angle NEXT to it? (degrees)
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180 − 130 = 50°.
9 What reason would you give for "x = 70°" when x is opposite a 70° angle at a crossing?
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Vertically opposite angles are equal.