Prove that


To Prove:

Taking LHS,


= 2 cos2 15° - 1 …(i)


We know that,


1 + cos 2x = 2 cos2x


Here, x = 15°


So, eq. (i) become


= [1 + cos 2(15°)] – 1


= 1 + cos 30° - 1


= cos 30°



= RHS


∴ LHS = RHS


Hence Proved


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