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Geometry and TrigonometryEasySupplementary angles in a given ratio

Geometry and Trigonometry practice question

Two angles are supplementary, and one of them measures 4 times the other. What is the measure, in degrees, of the smaller angle?

Answer: 36

Let the smaller angle be x. The larger is 4x, and supplementary angles add to 180: x + 4x = 180, so 5x = 180 and x = 36.

Common wrong answers

If you answered 18
18 treats the angles as complementary (adding to 90). Supplementary angles add to 180.
If you answered 45
45 is 180 / 4, which ignores the smaller angle itself. The two angles together make 5 parts: 180 / 5 = 36.
If you answered 144
144 is the LARGER angle (4 × 36). The question asks for the smaller one.

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