Question

Help me to solve the problem.​

Answer 1

Answer:

The answer is $A=65^\circ$

Step-by-step explanation:

Given $1+\tan^225^\circ=\cos ec^2A$

Using the identity $\sec^2\theta-\tan^2\theta=1\Rightarrow \sec^2\theta=1+\tan^2\theta$, we have

       $\Rightarrow \sec^225^\circ=\cos ec^2A$

       $\Rightarrow \sec^2(90^\circ-65^\circ)=\cos ec^2A$

Using $\sec (90^\circ-\theta)=\cos ec\theta$ we have

        $\Rightarrow \cos ec^265^\circ=\cos ec^2A\\\Rightarrow A=65^\circ$