Question

cos 15 degree
$cos15degree$​

Answer 1

Answer:

(√3+1)/2√2

Step-by-step explanation:

cos15° = cos(45-30)°

as we know that , cos(a-b) = cos a*cos*b + sin a*sin b

so ,

cos15° = 1/√2 * √3/2 + 1/√2 * 1/2

= √3 / 2√2 + 1 / 2√2

= (√3+1)/2√2