00:01
I'm given the following right triangle with sides 3x, x plus 1, x plus 9, and we're asked to find the actual lengths of all the sides.
00:08
So in order to do that, we have to find the value of x.
00:12
So we're going to use the thagrin theorem.
00:14
So a squared plus b squared is equal to c squared.
00:18
C is always across the 90 degree angle.
00:21
So x plus 9 is c.
00:23
A and b doesn't matter which one's which.
00:26
So i'm going to have 3x squared plus x plus 1 squared is equal.
00:32
Equal to x plus 9 squared.
00:35
So 3x squared is 9x squared.
00:38
X plus 1 squared.
00:40
We use the rule of the square of a binomial.
00:42
So take the first term and square it.
00:45
Multiply the first term in the second term and double it.
00:47
So you get 2x.
00:49
Take the last term and square it.
00:50
So that's plus one.
00:52
The other side we do the same thing.
00:53
Take the first term and square it.
00:55
Multiply the first term and the last term.
00:57
You get 9x and double it.
00:59
So that becomes 18x.
01:02
Take the last term.
01:03
That becomes 81.
01:06
So i'm going to move the x squared over...