Question

evaluate 2cos (2pi/3 - pi/2)

Answer 1

I would try and clear out the parentheses. 2pi/3 is 1/3 of a circle or 1/3 of 360 or 120 degrees, and pi over 2 (pi/2) is the same as 90 degrees so the value in the parentheses is 30 degrees, 2cos (30 degrees). Cos 30 is (sq rt 3)/2 so 2 cos(30) is sq rt 3 or\[\sqrt{3}\]