00:01
All right, so the problem we're given is a telephone pole that is 10 meters tall, has a 17 meter shadow, and the angle of it is 42 degrees from origin flat.
00:19
And we need to solve for theta.
00:24
Now, it gives us another angle of 42 minus theta for just this top triangle, which i drew over here.
00:31
And all we need to do is find that theta to solve the problem.
00:37
And so using this top triangle here with the 42 minus theta, we have to do the sine rule.
00:44
So we have angle a here and angle b here.
00:54
And the way that we're going to do the sign rule, which is sine a, the sign of angle a over side a is equal to so.
01:08
Sign of angle b over side b so we have angle b and angle a and the side that co corresponds to it is the one that it's pointing to so the open angle here is pointing to the 17 and the open angle here is pointing to the 10 so those are the numbers we plug in so you'll have sign a of angle a becomes sign of 48 over side a which is 17 is equal to sign of angle b 42 minus theta over side b which is now 10.
02:11
So your next step you're going to do is you're going to take these values and you need to get this sign 42 minus theta on its own and you're going to treat this as a number for now.
02:26
So in order to do that, we need to multiply both sides by 10 so that it can go away on this side.
02:36
Multiply by 10 over here...