How do you evaluate the sine, cosine, and tangent of the angle θ = −10π/3 without using a calculator?

1 Answer
Nghi N.
Sep 26, 2015

Find sin, cos and tan of ((-10pi)/3)

Explanation:

Trig unit circle -->
sin ((-10pi)/3) = sin ((-4pi)/3 - 2pi)=
= sin ((-4pi)/3) = sin (pi/3) = sqrt3/2

cos ((-10pi)/3) = cos ((-4pi)/3 - 2pi) = cos ((-4pi)/3) =
= - cos (pi/3) = -1/2
tan ((-10pi)/3) = sin/(cos) = (sqrt3/2)(-2/1) = -sqrt3

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