00:01
If we know that segment am bisects angle lar, then as i've got marked here in red, angles r -a -m -n -m -a -l are the same.
00:14
And if a s -bisex angle m -a -r, then what i've got double -marked is the same.
00:20
But actually, that would mean that the x plus 3 that we have and the 5x plus minus 7, which is the whole angle, you could fit four of them into it.
00:31
So when you're making an equation to find x, if you say, well, 5x minus 7 is the whole angle ral, then if we multiply that small x plus 3 angle and multiply it by 4, they will be equivalent.
00:47
They'll be the same.
00:49
So 4x plus 12 is equal to 5x minus 7 after we distribute the 4.
00:55
Subtract 4x to both sides and you get x minus 7...