Question

Find the value of x in each of the following:
cos2x=cos60°cos30°+sin60°sin30°

Answer 1

Answer:

15° is the correct answer of the given question

Answer 2

x= 15°

Step-by-step explanation:

Given: cos2x = cos60°.cos30°+ sin60°.sin30°

Cos 30°= √3/2  

cos 60° = 1/2

sin 30° = 1/2

sin 60° = √3/2

So RHS = cos60°.cos30°+ sin60°.sin30°

  = 1/2 * √3/2 + √3/2 * 1/2

  = √3/4 + √3/4

  = 2√3/4

  = √3/2

 So we get cos2x  = √3/2

  Cos 30°= √3/2  

  Therefore 2x = 30°

    x= 15°