Use pythagorean theorem to find perimeter

36

Step-by-step explanation:

Counting the squares: base = 12, height = 9.

We will use pythagorean theorem to find the third side.

Let it be x.

So,

Perimeter of triangle = sum lengths of all sides

                                = 12 + 9 + 15

                                = 36 units

560

hope this : )