Cos2A is equivalent to: A. sin2A−cos2A B. sin2A+cos2A C. cos2A−sin2A D. cosA−sinA

C.

Step-by-step explanation:

Given:

To find:

The given expression is equivalent to:

A.

B.

C.

D.

Solution/Proof:

First of all, let us have a look at the compound angle formula for .

Compound angle means in which there is sum of two angles given.

In the above we are having X+Y i.e. sum of two angles X and Y. So it is compound angle.

The compound angle formula for cosine is given as:

Here, let us put X = Y = A

So, cos2A is equivalent to .

Correct answer is:

Option C.

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