Question

use exact values of the sin,cos and tan of (pi/3) and (pi/6)(which I have found)and the symmetry of the graphs of sin,cos and tan to find the exact values of sin(-pi/6), cos(5pi/3) and tan (4pi/3). I know that sin -(pi/6) = -1/2 and cos (5pi/30 = 1/2 and tan 4pi/3 = root 3 but I don't know how to the graphs using excel. I found out the answers using my calculator