How do you use Heron's formula to find the area of a triangle with sides of lengths #9 #, #3 #, 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=(9+3+9)/2=21/2#
which gives an area of
#A=sqrt(21/2(21/2-9)(21/2-3)(21/2-9))#
#A=sqrt(21/2(3/2)(15/2)(3/2))#
#A=sqrt((9^2xx7xx5)/4^2)#
#A=(9sqrt35)/4approx13.3112#