SOLVING

Find the missing side of the triangle.

We should find the leg of this right triangle, not the hypotenuse.
The hypotenuse, the longest side, is already given to us.
We can find it using Pythagoras' Theorem:
.
We know b and c, we need to find a.
| square
| subtract 81
| square-root both sides

And we should automatically cross out this extraneous solution of "a=-12", because side lengths can't be negative!



