If cos α = 0.923 and cos β = 0.624 with both angles’ terminal rays in Quadrant-I, find the values of (a) cos ( α + β ) = (b) cos ( β − α ) =

Question

I need to find it the the 4th decimal any help would be appreciated?

Answer 1

cos α = 0.923, sin α = 0.385

cos β = 0.385, sin β = 0.781

Now substitute values into appropriate formulas.