Geometry and TrigonometryEasy–MediumAdjacent angles on a line in a ratio
Geometry and Trigonometry practice question
Two adjacent angles together form a straight angle, and one of them measures four times the other. What is the measure, in degrees, of the smaller angle?
Answer: 36
Let the smaller be x; the larger is 4x. Adjacent angles on a straight line add to 180: x + 4x = 180, so x = 36.
Common wrong answers
- If you answered 18
- 18 uses 90 as the total; a straight angle is 180.
- If you answered 45
- 45 is 180/4, ignoring the smaller angle's own share of the 180.
- If you answered 144
- 144 is the LARGER angle (4 × 36).
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