Do you remember that cos(a-b)=cos(a)cos(b) + sin(a)sin(b) ?
Find the exact value of Cos 53 Cos 8 + Sin 53 Sin 8. I was told that the answer to the problem is Sqrt2/2. When I solve the problem I get
Cos 61 + Sin 61
which is about 60
then Cos 61 approx 1/2 and Sin of 61 is approx sqrt3/2 which I do not get to equal sqrt2/2.
Can someone please help and explain to me what I need to do or what the correct answer is? Thank you for your help