Question

show that cos²x=cos²x-sin²x​

Answer 1

Answer:

mate your question is not correct please make it correct

Answer 2

Answer:

This proof is not possible for any value of x.

I think it is $cos(2x)=cos^{2}x-sin^{2}x$

Step-by-step explanation:

$cos^{2} x=cos^{2}x - sin^{2}x$

⇒$cos^{2}x + sin^{2}x= cos^{2}x$

⇒$cos^{2}x=1$

⇒$cos x = +1, -1$

⇒$x=0; 2\pi$

$cos(2x)=cos(x+x)$

            $=cosx*cosx - sinx*sinx$         $[cos(A+B)=cosAcosB-sinAsinB]$  

            $=cos^{2}x -sin^{2}x$