Question #8b831

1 Answer
Feb 12, 2017

cos15=cos(4530)

expanding by using

cos(xy)=cosxcosy+sinxsiny

Explanation:

cos(4530)=cos45cos30+sin45sin30

use the standard angle values for cosine and sine

cos(4530)=22.32+22.12

factorise

cos(4530)=142(3+1)

multiply 2 into the bracket to arrive at required solution

cos(4530)=14(6+2)