Is the function f(x) = 2 cot xf(x)=2cotx even, odd or neither?

1 Answer
Nov 14, 2015

2cot(x)2cot(x) is an odd function.

Explanation:

A function f(x)f(x) is even if and only if f(-x) = f(x)f(x)=f(x)
A function f(x)f(x) is odd if and only if f(-x) = -f(x)f(x)=f(x)

Note that sin(x)sin(x) is an odd function and cos(x)cos(x) is even.

Thus we have
f(-x) = 2cot(-x) = 2cos(-x)/sin(-x)f(x)=2cot(x)=2cos(x)sin(x)

Because sine is an odd function and cosine is even, we have

f(-x)= 2cos(x)/(-sin(x)) = -(2cos(x)/sin(x)) = -f(x)f(x)=2cos(x)sin(x)=(2cos(x)sin(x))=f(x)

Thus 2cot(x)2cot(x) is odd.