# How do you use Heron's formula to find the area of a triangle with sides of lengths #7 #, #4 #, and #9 #?

##### 1 Answer

Jan 24, 2016

#### Explanation:

Heron's formula states that for a triangle with sides

#A=sqrt(s(s-a)(s-b)(s-c))#

Here, we know that

#s=(7+4+9)/2=10#

which gives an area of

#A=sqrt(10(10-7)(10-4)(10-9)#

#A=sqrt(10xx3xx6xx1)#

#A=6sqrt5approx13.4164#