Question

How do you simplify `cot(x+y)` to trigonometric functions of x and y?

Answer 1

`(1 - tan x.tan y)/(tan x + tan y)`

Explanation:

Trig identity -->
`tan (x + y) = (tan x + tan y)/(1 - tan x.tan y)`
Then,
`cot (x + y) = 1/(tan (x + y)) = (1 - tan x.tan y)/(tan x + tan y)`