If cos θ = (x² – y²)/(x² + y²) then the value of cot θ is…

If cos θ = (x² – y²)/(x² + y²) then the value of cot θ is equal to [If 0° ≤ θ ≤ 90°]

Show answer & explanation

Correct answer: D

Explanation

The correct answer is option 4 i.e. (x² – y²)/2xy

Understanding

Application

We know that:

Cos X = Base/Hypotenuse

And

Cot X = Base/Perpendicular

Given:

cos θ = (x² – y²)/(x² + y²)

So,

Base = (x² – y²)

Hypotenuse = (x² + y²)

Now,

Perpendicular = 2xy (Using Pythagoras theorem)

So,

Cot θ = (x² – y²)/2xy

SSC CGL 2017 PYQ — Question 90