Geometry and TrigonometryEasyThree angles on a straight line
Geometry and Trigonometry practice question
Three angles together form a straight angle. Two of them measure 45° and 60°. What is the measure, in degrees, of the third angle?
Answer: 75
A straight angle is 180°. The third angle is 180 − 45 − 60 = 75°.
Common wrong answers
- If you answered 105
- 105 is 45 + 60, the two known angles added together, not the third one.
- If you answered 120
- 120 is 180 − 60, forgetting the 45° angle.
- If you answered 135
- 135 is 180 − 45, forgetting to subtract the 60° angle as well.
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