## Calculus 8th Edition

$cot^{2}\theta+sec^{2}\theta=tan^{2}\theta+csc^{2}\theta$
Need to prove the identity $cot^{2}\theta+sec^{2}\theta=tan^{2}\theta+csc^{2}\theta$ In order to prove this, take left side isolate. $cot^{2}\theta+sec^{2}\theta=(csc^{2}\theta-1)+(tan^{2}\theta-1)$ $cot^{2}\theta+sec^{2}\theta=csc^{2}\theta+tan^{2}\theta$ Hence, $cot^{2}\theta+sec^{2}\theta=tan^{2}\theta+csc^{2}\theta$