# Math Help - Simple question??

1. ## Simple question??

Hi guys

Its revision time, and I've been going through previous papers for the module. One cropped up asking for an angle, given $sin^2(x)=0.64$. I know how I'd go about it if it was simply sin... but i just dont know the inverse of $sin^2 (x)$!!
None of my coursemates know either, but I cant ignore it and hope it doesnt come up really!

Any help on the matter would be appreciated!

Thanks

2. Hi

When solving something like $X^2=100$, you find the solutions saying that $X=\pm\sqrt{100}=\pm10$. You're in this situation here, except that $X=\sin x$ and that 100 has been replaced by 0.64 :

$\sin^2x=0.64 \Leftrightarrow \sin x=\pm \sqrt{0.64}=\pm 0.8$

It gives you two equations to solve, good luck !

3. Genius, cheers!

I was looking for an identity