Question

find the value of cos 15°​

Answer 1

Step-by-step explanation:

cos (a-b) = cos a * cos b + sin a *sin b

cos 15 = cos (45–30)

=> cos 15 = cos 45 * cos 30 + sin 45 * sin 30

=> cos 15 = (1/√2)* (√3/2) + (1/√2)*(1/2)

cos (a-b) = cos a * cos b + sin a *sin b

cos 15 = cos (45–30)

Answer 2

Step-by-step explanation:

We know that

cos (a-b) = cos a * cos b + sin a *sin b

cos 15 = cos (45–30)

=> cos 15 = cos 45 * cos 30 + sin 45 * sin 30

=> cos 15 = (1/√2)* (√3/2) + (1/√2)*(1/2)

=> cos 15 = (√3 + 1 )/2√2

Hope it helps !!!