00:01
Okay, here i want to write theta in terms of x.
00:04
We know a tan theta is opposite over adjacent, so x over 4, which means theta will be inverse tan of x divided by 4.
00:19
That's the answer here, inverse tan of x over 4.
00:25
Now, the next one says, find the exact value of sine, arc tan, of 3.
00:32
Quarters.
00:34
Here what you do, you call this item here a.
00:39
So somehow i want to work out the value of sign a.
00:43
Well, from here, i can see that tan of a must be three quarters.
00:51
If a is arc tan three quarters, it means tan a is three quarters.
00:55
Now, here i'll draw a triangle.
00:59
It'll very well.
01:02
Like this, here is angle a.
01:05
Tan a opposite over adjacent, with three over four.
01:09
So third side from pythagoras is 5.
01:13
3 squared plus 4 square is 25.
01:17
Square root is 5.
01:19
So i want to work out the value of sine a...