Question

What is the value of cos(45-beta)​

Answer 1

Explanation:

cos (x-y)=cos x cos y+sin x sin y

cos(45-β)=cos~45~cos~β+sin~45~sin~β

`cos~45=sin~45=(1)/(√(2) )\\cos (45-\beta )=(1)/(√(2) ) ~cos~\beta +(1)/(√(2) ) ~sin~\beta \\=(1)/(√(2) ) (cos~\beta +sin~\beta )`