Question

find the velues os cos 75​

Answer 1

cos 75 = cos (45+30)

= cos 45 cos 30 - sin 45 sin 30

= 1/√2 x √3/2 - 1/√2 x 1/2

= √3/2√2 - 1/2√2

= (√3-1)/(2√2)