Question

How do you express `cos(pi/ 2 ) * cos (( pi) / 6 )` without using products of trigonometric functions?

Answer 1

`cos(pi/2) * cos(pi/6) = color(green)(0)`

Explanation:

`pi/2` and `pi/6` are standard angles
with
`color(white)("XXX")cos(pi/2)=0`
and
`color(white)("XXX")cos(pi/6)=sqrt(3)/2`

So
`color(white)("XXX")cos(pi/2) * cos(pi/6) = 0 xx sqrt(3)/2 =0`