# How do you multiply and simplify #(tany-coty)(tany+coty)#?

##### 1 Answer

Mar 28, 2018

# (tany-coty)(tany+coty) -= tan^2y-cot^2y #

#### Explanation:

We have an expression,

# E = (tany-coty)(tany+coty) #

This is the difference of two squares, thus we can write:

# E = tan^2y-cot^2y #

The issue of "simplify" is somewhat ambiguous - there are many other ways we can write the expression!