Question

If $a \sin\theta + b \cos\theta = c$, then $(a \cos\theta - b \sin\theta)^2 = ?$

• A. $a^2 - b^2 + c^2$
• B. $a^2 + b^2 - c^2$
• C. $a^2 - b^2 - c^2$
• D. $a^2 + b^2 + c^2$

Hint:

The sum of squares of $a\sin\theta+b\cos\theta$ and $a\cos\theta-b\sin\theta$ is always $a^2+b^2$.

Answer 1

The Correct Option is B