00:01
Calculate sign of 300 and cosine of 300 without a calculator using a reference angle instead.
00:07
So i'm going to begin by drawing the angle of 300 degrees so we can determine its reference angle and also which quadrant it falls in.
00:17
So we'll have our initial side on the positive x -axis.
00:22
This would be an angle of 90 degrees, 180, 270, so another 30 degrees would get us that angle of 300 degrees.
00:31
Now the reference angle is how much more it takes to get back to that x -axis, which would be in this case another 60 degrees to get to 360 or one full rotation.
00:49
So that leaves us with a 30, 60, 90 triangle.
01:00
Being a special triangle that allows us to determine all the sides of said triangle.
01:05
So across from 30 degree angle is a one.
01:11
Across from the 60 degree angle is twice that, so 2.
01:18
And across from our 90 degree angle is the square root of 3.
01:32
Across from your 90 degree angle is the 2, and across from the 60 degree angle is the square root of 3.
01:44
What we need to be careful with is the quadrant that we're in...