Question

What is cos of negative pi/3?
what is sin of negative pi/3?

Answer 1

Cosine is even function, so:


`$\cos(-(\pi)/(3))=\cos((\pi)/(3))=(1)/(2)`

and sine is odd function, so:


`$\sin(-(\pi)/(3))=-\sin((\pi)/(3))=-(√(3))/(2)`

Answer 2

pi/3 is equivalent to 60 degrees, as 2pi is equal to 360 degrees. cos(60) in a triangle yields 1/2, and sin(60) yields (3^(1/2))/2. Thus, -pi/3, or -60 degrees would be a fourth quadrant point on the unit circle and these values would be negative as well, at cos(-pi/3)=-1/2 and sin(-pi/3)=-(3^(1/2))/2