How to Find the Area of a Scalene Triangle

Half Base Times Height Method

• 1

  Use the "half base times height" method if the base and height of the scalene triangle are known.

• 2

  Multiply the length of the base of the triangle by the height of the triangle.

• 3

  Divide the result by 2 to obtain the area of the scalene triangle.

Side-Side-Angle Method

• 4

  Use the "side-angle-side" method if two sides and the included angle are known. An included angle is the angle that is "sandwiched" between two rays.

• 5

  Multiply the lengths of the two known legs together then multiply the result by the sine of the included angle.

• 6

  Divide the result by 2 to obtain the area of the scalene triangle.

Heron's Formula Method

• 7

  Use Heron's Formula if all three sides of the scalene triangle are known.

• 8

  Find half of the perimeter "p" of the triangle by adding the three sides together then dividing the result by 2.

• 9

  Subtract each of the values of the side length from "p." Then multiply the results together. For example, if the side lengths of a scalene triangle are "a," "b," and "c" and the half perimeter is "p," the expression becomes: (p - a) * (p - b) * (p - c).

• 10

  Multiple the result of the previous expression by the value of "p."

• 11

  Take the square root of the result to obtain the area of the scalene triangle.