We can count the bottom units to get 10 units. Now to get the sides of it.
Let’s split this triangle in the middle to get two right triangles.
The height of the triangle is 12 units and one of the legs is 5 ( from 10/2 )
Let’s find the hypotenuse
(5) ^2 + (12) ^2 = c^2
C = 13
So this mean each side is 13 units
13 + 13 + 10 = 36 units
Perimeter = 36 units
