Question

find the value of cos 75 degree by using Cos A + B formula​

Answer 1

Answer:

(√6 - √2)/4

Step-by-step explanation:

Cos(A+B) = CosACosB - SInASinB.

Cos 75° = Cos (30 + 45) = Cos30Cos45 - Sin30Sin45

                                       = (√3/2)(1/√2) - (1/2)(1/√2)

                                       = √3 - 1/2√2

                                        = √6 - √2/4