Here we are given the three sides of the triangle.
So we have Heron's formula to find its area.
Heron's formula is given by :
[tex] A= \sqrt{S(S-A)(S-B)(S-C)} [/tex]
where A, B and C are sides of triangle and S is semi perimeter which is given by,
[tex] S= \frac{A+B+C}{2} [/tex]
plugging values of A, B and C to find S
[tex] S= \frac{9+6+12}{2} [/tex]
S=13.5
Now plugging values of A, B , C and S in Heron's formula
[tex] A= \sqrt{13.5(13.5-9)(13.5-6)(13.5-12)} [/tex]
A=26.14 mm²
Answer: Area of triangle is 26.14 mm².
