Question

If two supplementary angles are in the ratio 4 : 5 then the angles are :-

• A. 80°, 100°
• B. 85°, 95°
• C. 40°, 50°
• D. 60°, 120°

Answer 1

The correct option is A

80°, 100°

Let the angles be 4x and 5x.

So, we know that 4x + 5x = 180${}^{\circ }$

⇒ 9x = 180${}^{\circ }$

⇒ x = 20${}^{\circ }$

⇒ 4x = 4 × 20${}^{\circ }$ = 80${}^{\circ }$, 5x = 5 × 20${}^{\circ }$ = 100${}^{\circ }$

So, angles are 80${}^{\circ }$ and 100${}^{\circ }$.