Expert: Socrates - 9/21/2007

Question
I have a problem that I cannot figure out for the life of me.  I don't want the answer, just a hint to get me in the right direction.  The question is: if sin of theta = -.79 and theta is in the 4th quadrant, find cos of theta and cot of theta.  I have no idea of how to even begin.  Thanks!

Answer
I will use "t" for the angle theta

You need to know that sin^2(t) + cos^2(t) = 1

So (-.79)^2 + cos^2(t) = 1

.6241 + cos^2(t) = 1

cos^2(t) = 1 - .6241

continue and solve for cos(t). Choose the "+" sign when you take the square root because the angle is in the fourth quadrant and you want cos to be positive. After you find the value of cos(t) , use cot(t) = cos(t)/sin(t) and get the other answer.