Question

I KNOW THE ANSWER, BUT I NEED TO KNOW HOW TO DO THIS: Determine the sign of cos pi divided by three without using a calculator.

Answer 1

Well, draw a unit circle and mark the angle \(\pi/3\) radians, then look and see whether the point on the unit circle is to the right or left of the origin. \(\cos\) represents the \(x\) coordinate of the point on the unit circle.