Question 729421
tan(theta) = 2 with theta in quadrant III, how do I find the sec(theta) and vice versa?
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Using a calculator, find theta. It'll show the principal angle, 63.4... degs
Add 180 --> 243.4 degs.
Get the cos with the calculator
sec = 1/cos = -2.236...
= -sqrt(5)
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or even this..

if cos(theta) = 4 with theta in quadrant IV, how can I solve for sin(theta) or csc(theta)? 

acos(4) is not a real number.