Question

The minimum value of $9ta{n}^2\theta +4co{t}^2\theta$ is

• A. 13
• B. 9
• C. 6
• D. 12

Answer 1

The correct option is D

12

A.M. $\ge$ G.M.

$\Rightarrow$ $\frac{9ta{n}^2\theta +4co{t}^2\theta }{2}$ $\ge$ $\sqrt{4co{t}^2\theta .9ta{n}^2\theta }$

$\Rightarrow$ $9ta{n}^2\theta +4co{t}^2\theta$ $\ge$ 12

Therefore, the minimum value is 12.