00:01
Suppose i know that sign of an angle equals negative 4 over 7, and tangent of that same angle is positive.
00:07
So first, let's determine which quadrant i'm in.
00:10
So i'm in the first, second, third, and there's four quadrants.
00:15
So sign is negative.
00:17
The sign relate to the x or the y -axis.
00:19
Well, it relates to the y -axis.
00:20
So the y -axis is negative.
00:22
So it's either the second or the third, and tangent is positive.
00:26
Recall that tangent is sine over cosine.
00:31
So if sign is negative, cosine also has to be negative, which is the x value, which will be the third quadrant.
00:37
So i'm in the third quadrant, so i can draw a right triangle with angle theta.
00:42
Sign is opposite over hypotenuse.
00:44
The opposite side is negative 4.
00:46
Hypotenuse is always positive, so that's how i know the 4 is negative.
00:49
And then let's say i wanted to solve for the missing side up here...