How do you use Heron's formula to determine the area of a triangle with sides of that are 7, 4, and 9 units in length?

1 Answer
Roella W.
Jan 19, 2016

A=4sqrt(15)

Explanation:

Heron's formula states the the area of a traiangle A can be calculated as
A = sqrt(p(p-a)(p-b)(p-c)) where p = (a+b+c)/2 and a, b and c are the three sides of the triangle.

So for this example
p = (7+4+9)/2 =10

A=sqrt(10(10-7)(10-4)(10-9)) = sqrt(10*4*6*1) =sqrt(240)

A=sqrt(16*15) = 4sqrt(15)

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