00:01
Okay, this i want to solve for theta between 0 and 360 degrees.
00:06
First thing we do is draw a grid with the four quadrants.
00:11
And you can see here is negative and sign is negative in the third and the fourth quadrants.
00:20
It's plus in 1 and 2 minus in 3 and 4.
00:24
And the first thing we do is find the reference angle, alpha, which goes here and here.
00:29
And to find alpha you do inverse sign of plus 0 .7 this number here so on a calculator in degree mode inverse sign of 0 .7 is going to be 44 .427 degrees what do they want here let's have a look okay at least three decimal places around to three decimal places so 42700 so we're fine with 427.
01:10
Now i want to find though theta and here we have 2 theta.
01:16
Well that means 2 theta will equal this angle around here which will be 180 plus the 44 .427 so that will be 224 .4 .27 that's one answer.
01:40
Or it could be this one around here like this, which will be 360 minus 44 .27, rather.
01:55
And that is 315 .573.
02:03
Now, that's the basic two answers, but i need to have two more because it's 2 theta and divided by 2 at the end.
02:09
So all i do for the next two is just add on 360 degrees to this one and that one.
02:18
In other words, what i'm doing is i'm going around one complete circle and around to there again.
02:26
So it's 360 plus the previous answer.
02:29
So 224 .427 plus 360 is going to be 584 .484 .4 .427...