
Stephen C. answered 08/18/19
SAT Math, Algebra, Trig, PreCalc Tutor
30-60 right triangles and 45-45 right triangles are so common and fundamental in trigonometry (and calculus, etc) that you will save a lot of time in the long run by memorizing these special angles and their trig function values, on the Unit Circle. Draw a unit circle (radius = 1), and then label these angles and their basic trig values.
Degrees Radians Cosine Sine
0 0 1 0
30 π / 6 √3 / 2 1 / 2 √3 / 2 is about .866
45 π / 4 √2 / 2 √2 / 2 √2 / 2 is about .707
60 π / 3 1 / 2 √3 / 2
90 π / 2 0 1