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