Answer:
A = 9.2 cm²Step-by-step explanation:
According to Heron's formula :
A = [s(s - a)(s - b)(s - c)]^½
Here a, b and c are the sides of the triangle, and,
s = (a + b + c)/2
a = k = 5.1 cm, b = l = 6.4 cm and c = m = 3.6 cm
So, s = (5.1 + 6.4 + 3.6)/2 = 7.55
Thus,
A = [7.55(7.55 - 5.1)(7.55 - 6.4)(7.55 - 3.6)]^½
On solving,
A = 9.2 cm²