00:01
All right, on this problem, we're told that we have a 15 -foot ladder leaning against a building.
00:04
Now, the place that the ladder hits on the top of the building, the length, the height above the ground that the ladder is off the wall.
00:13
This height here is three feet more than the distance from the base of the ladder to the wall.
00:20
And so that's why i have x plus three for the vertical part and the next for the bottom, because the vertical part is three feet longer than the other.
00:27
Now to set up our equation, we use pythagorean theorem.
00:30
And so it says the light squared plus the other light squared in the right triangle is equal to the hypotenuse squared.
00:41
So we've got a squared plus b squared is c squared.
00:44
And then now we need to solve this.
00:46
So we have x squared plus...
00:49
Now x plus 3 squared for this part.
00:51
You've got to take x plus 3, multiply it by itself, and foil it out.
00:57
So it'd be x squared plus 6x plus 9 whenever you do that.
01:01
Squared plus 6x plus 9 and then equals 15 squared which is 225 so x squared plus x squared plus 9 is 225 now let's combine like terms and get it equal to zero because we've got a quadratic to solve so x squared plus x squared is 2x squared and then we've got plus 6x let me take this 225 over should be minus 216 is equal to 0.
01:36
2x squared plus 6x minus 216 is equal to 0...