Question 254156
The question was:
(i) {{{cos(45 + 30)}}}
We have the following identity:
{{{cos(A+B) = cosAcosB - sinA sinB}}}
So, (i) becomes
(ii) {{{cos(45 + 30) = cos45cos30 - sin45 sin30}}}
or
{{{cos(45 + 30) = (sqrt(2)/2)*(sqrt(3)/2) - (sqrt(2)/2)*(1/2)}}}
which is
{{{cos(45 + 30) = (sqrt(6) - sqrt(2))/4}}}