Area of a Triangle

Key Questions

  • Heron's formula allows you to evaluate the area of a triangle knowing the length of its three sides.
    The area A of a triangle with sides of lengths a, b and c is given by:

    A=sqrt(sp×(sp-a)×(sp-b)×(sp-c))

    Where sp is the semiperimeter:

    sp=(a+b+c)/2

    For example; consider the triangle:
    enter image source here
    The area of this triangle is A=(base×height)/2
    So: A=(4×3)/2=6
    Using Heron's formula:
    sp=(3+4+5)/2=6
    And:
    A=sqrt(6×(6-5)×(6-4)×(6-3))=6

    The demonstration of Heron's formula can be found in textbooks of geometry or maths or in many websites. If you need it have a look at:
    http://en.m.wikipedia.org/wiki/Heron%27s_formula

  • You can use it whenever you know the lengths of all three sides of a triangle.


    I hope that this was helpful.

Questions