evaluate the trigonometric function of the given quadrantal angle.

Question

tan 1400°
cos 9π
cos 13π/2
sin (-17π)

Answer 1

subtract multiple of 360° (1400/360 = 3.8..
so
tan 1400°
= tan320° , 320 is in IV and 40° from the x-axis
= -tan40
= ....

cos 9π
= cos π , (took away 4 multiples of 2π)
= -1

cos 13π/2
= cos π/2 (took away 6π)
= 0

sin(-17π)
= sin(-17π + 18π) , ( I added 9 rotations)
= sin π
= 0