How do you express cos(pi/ 2 ) * cos (( 17 pi) / 12 ) without using products of trigonometric functions?
1 Answer
Jan 5, 2016
Explanation:
Use the rule:
cos(a)cos(b)=1/2(cos(a+b)+cos(a-b))
Thus,
cos(pi/2)cos((17pi)/12)=1/2(cos(pi/2+(17pi)/12)+cos(pi/2-(17pi)/12))
=1/2(cos((23pi)/12)+cos((-11pi)/12))
This could continue to be simplified using half angle formulas, but this answer is fine as is given the parameters ("without using products of trigonometric functions").
