Question

cos^(2)x = 0 ???

Answer 1

Well, I know that cos90=0
so cos^2x=cos90
can you solve for x now?

Answer 2

\(\bf cos^2(x)=0\implies cos(x)=\sqrt{0}\implies cos(x)=0\\ \quad \\
cos^{-1}[cos(x)]=cos^{-1}(0)\implies x=cos^{-1}(0)\)

Answer 3

I made it even harder, my bad.

Answer 4

then cos^(2)x=0 is the same as cosx=0 or is bad?

Answer 5

well, all I did is take square root to both sides, to isolate the cosine part, so \(\bf cos^2(x)=0\implies \sqrt{cos^2(x)}=\sqrt{0}
\implies cos(x)=0\\ \quad \\
cos^{-1}[cos(x)]=cos^{-1}(0)\implies x=cos^{-1}(0)\)

Answer 6

\(\bf 0 = 0^2\qquad thus\qquad \sqrt{0}\implies \sqrt{0^2}=0\)