The perimeter of a triangle is the sum of the length of its three sides, whether they are equal or not.

Equilateral |
Isosceles |
Scalene |

The area of a triangle is equal to the basis multiplied by the height divided by $$2$$.

$$$A=\dfrac{b \cdot h}{2}$$$

## Semiperimeter of a triangle

The semiperimeter of a triangle is equal to the sum of its sides divided by $$2$$.

It is normally denoted with the letter p (in lower case) and we express it as:

$$$p= \dfrac{a+b+c}{2}$$$