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 :
where A, B and C are sides of triangle and S is semi perimeter which is given by,
plugging values of A, B and C to find S
S=13.5
Now plugging values of A, B , C and S in Heron's formula
A=26.14 mm²
Answer: Area of triangle is 26.14 mm².