How do you evaluate sine, cosine, tangent of #-(3pi)/2# without using a calculator?

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Answer 1 · 2018-05-25T17:55:01

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Given: #theta = -(3 pi)/2#

The angle #-(3 pi)/2 = -270^@ " or " 270^@# clockwise (CW).

#270^@# CW #= 90^@# counterclockwise (CCW) or #pi/2#

On a unit circle, this represents the point #(0, 1)# with #r = 1#

#sin -(3 pi)/2 = y/r = 1/1 = 1#

#cos -(3 pi)/2 = x/r = 0/1 = 0#

#tan -(3 pi)/2 = y/x = 1/0 = "undefined"#