# What is the answer of 1-cot²a=?

##### 2 Answers

Jun 21, 2018

It helps to rewrite in terms of sine and cosine.

#1 -cot^2a = 1-cos^2a/sin^2a = (sin^2a -cos^2a)/sin^2a =-(cos^2a -sin^2a)/sin^2a = -cos(2a)/sin^2a#

Hopefully this helps

Jun 21, 2018

#### Explanation:

First answer:

We can go further: