Using the formula,, find the value of cos 30°, it being given that cos 60° = 1/2 .
Given: cos A = , …………………….(1)
cos 60° = 1/2
To find: cos 30°
By putting A = 30° in equation (1), we get the following:
cos 30° =
=
= = √3/2
∴ cos 30° = √3/2