I'm trying to find out which quadrant some trigonometric functions lie in. The problem is one of them is equal to zero, and zero is neither positive or negative. How do I determine which quadrant it belongs in then???

Answer 1

I suggest that you "memorize" the shape and graph of the sine, cosine and tangent functions.
That way you can tell where the angle ß in such equations as sinß = 0 is.

You are correct to notice that those angles do not lie in a particular quadrants, so they are considered special cases.

e.g. sin 180º = 0
while sin 179º is positive
and sin 181º is negative.
We would have not problem deciding where 179 and 181 lie, would we?