Q14 of 153 Page 113

Two complementary angles are in the ratio 4:5 Find the angles.

40°, 50°


Let angle = X


Complementary of X = 90° – X


According to question,


X : 90° – X = 4 : 5


⇒ X / (90° – X) = 4 / 5


⇒ 5X = 4(90° – X)


⇒ 5X = 360° – 4X


⇒ 5X + 4X = 360°


⇒ 9X = 360°


⇒ X = 40°


Therefore angle = 40°


And its supplement = 90° – 40° = 50°


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