Lesson 8. Perimeter and Area. Perimeter. The perimeter of a closed figure is the distance around the outside of the figure. In the case of a polygon, the perimeter is found by adding the lengths of all of its sides. No special formulas are needed.
Perimeter and Area
hAltitudes of Triangles
where b is the length of the base (one of the sides of the triangle) and h is the height (the length of the altitude drawn to the base).
where s is the semiperimeter: