Question

If in ∆ABC, ∠A = 90⁰ and c, sin B, cos B are rational

numbers, then

• A. A is rational and b is irrational
• B. A is irrational and b is rational
• C. A and b both are rational
• D. None of these

Answer 1

Answer: (C)

A and b both are rational

Answer 2

Here C = 90⁰ – B and sin C = cos B.

Also a = $\frac{b}{\sin B} = \frac{c}{\sin C} = \frac{c}{\cos B}$

⇒ a, b are rational