Question

What are the exact values of `cos((3pi)/4)` radians and `sin((3pi)/4)` radians?

Answer 1

`cos((3pi)/4)=-sqrt2/2`

`sin((3pi)/4)=sqrt2/2`

Explanation:

`cos((3pi)/4)=cos(pi-pi/4)=-cos(pi/4)=-sqrt2/2`

`sin((3pi)/4)=sin(pi-pi/4)=sin(pi/4)=sqrt2/2`

Imagine the trigonometric circle in your mind.