Question

If cos 30 degree is equal to root 3 by 2 then the find the answer cos 15 degree equal to 1 upon 2 under root 2 + root 3

Answer 1

Answer:

hey Mate here is ur ans

cos 30° = √3/2

cos15° = cos(45-30)°

=cos45°cos30°+sin45°sin30°

= 1/√2×√3/2 + 1/√2×1/2

= √3/2√2+1/2√2

= √3+1/2√2

ON RATIONALIZING

= √3+1/2√2×√3-1/√3-1

= 3-1/2√2(√3-1)

= 1/√6-√2

hope it help u