Question

Two angles are complementary and their sizes are in the ratio 5 : 7. What is the size of the smaller of the two angles?

• A. 42.5
• B. 18
• C. 37.5
• D. 35

Answer 1

The correct option is C

37.5

Let the angles be 5x° and 7x° Since they are complementary, they must add to 90° So 5x° + 7x° = 90° ? 12x° = 90° ? x° = 90° ÷ 12 = 7.5° We want the smaller angle, which is 5x° = 5 × 7.5° = 37.5° (And the larger angle is 7x° = 52.5°, together they make 37.5°+52.5° = 90°)