Question

$9{\sec }^2\theta -9{\tan }^2\theta$ is equal to

• A. 1
• B. -1
• C. -9
• D. 9

Answer 1

The correct option is D 9

$9se{c}^2\theta -9ta{n}^2\theta$

$\Rightarrow 9(se{c}^2\theta -ta{n}^2\theta )$

$\because se{c}^2\theta -ta{n}^2\theta =1$

$\therefore 9\left(1\right)=9$