A triangle has sides with lengths: 6, 11, and 9. How do you find the area of the triangle using Heron's formula?

1 Answer
Jan 5, 2016

A=2sqrt182A=2182

Explanation:

First, find the triangle's semiperimeter. The semiperimeter is one half the perimeter of the triangle, which can be represented for a triangle with sides a,b,a,b, and cc as

s=(a+b+c)/2s=a+b+c2

Thus,

s=(6+11+9)/2=13s=6+11+92=13

Now, use Heron's formula to determine the area of the triangle. Heron's formula uses only the side lengths of the triangle to find the triangle's area:

A=sqrt(s(s-a)(s-b)(s-c))A=s(sa)(sb)(sc)

A=sqrt(13(13-6)(13-11)(13-9))A=13(136)(1311)(139)

A=sqrt(13xx7xx2xx4)A=13×7×2×4

A=2sqrt182A=2182