# Is #f(x)=cot(2x)*tanx# increasing or decreasing at #x=pi/6#?

##### 1 Answer

Jun 2, 2017

#### Explanation:

Whether a function is increasing or decreasing at a point is decided by its first derivative at that point.

As

#=(1-tan^2x)/(2tanx)xx2tanx=(1-tan^2x)/2=1/2-1/2tan^2x#

Hence,

and

As

Observe that

graph{cot(2x)*tanx [-2.5, 2.5, -1.25, 1.25]}