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 $r = 1$

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

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

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

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