How do you use Heron's formula to find the area of a triangle with sides of lengths 4, 8, and 5?

1 Answer
Feb 12, 2016

A=8.1815

Explanation:

Heron's formula is A=s(sa)(sb)(sc), where A is area, a,b,andc are the sides, and s is the semiperimeter, which is the perimeter divided by 2. Side a=4, side b=8, and side c=5.

First determine s.
s=a+b+c2

s=4+8+52

s=172

s=8.5

Use Heron's formula to find the area of the triangle.

A=s(sa)(sb)(sc)

Substitute the known values into the equation.

A=(8.5)(8.54)(8.58)(8.55)

Simplify.

A=(8.5)(4.5)(0.5)(3.5)

Simplify.

A=66.9375

Take the square root.

A=8.1815 square units to four decimal places.