## Algebra 2 Common Core

By identity, $csc\theta=\frac{1}{sin\theta}$ $$=\frac{1}{sin^{2}\theta}\times(1-cos^{2}\theta)$$ By identity, $sin^{2}\theta+cos^{2}\theta=1$ (Rearrange and replace 1-$cos^{2}\theta$ with $sin^{2}\theta$, $$=\frac{sin^{2}\theta}{sin^{2}\theta}=1$$