How do you calculate tan(cos^-1(-3/5))tan(cos−1(−35))?

1 Answer
Alan P.
Jul 22, 2015

tan(cos^(-1)(-3/5)) = +- 4/3tan(cos−1(−35))=±43

Explanation:

If cos(theta) = -3/5cos(θ)=−35
then thetaθ must be one of the angles indicated in the diagram below (either in the second or third quadrant).

Both associate triangles are standard 3-4-53−4−5 right angled triangles
and depending upon whether the angle is in the second or third quadrant,
the tantan will be either 4/545 or -4/5−45
enter image source here

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