The sides of a triangle are in the ratio 3 : 4 : 5 and its perimeter is 144 cm. What is the area of the triangle?

Answer: B. 864 cm²

Answer: B) 864 cm²
Explanation: Let the sides be 3x, 4x and 5x. Then 12x = 144, so x = 12 and the sides are 36 cm, 48 cm and 60 cm.
s = 72 cm. By Heron's formula, Area = √(72 × 36 × 24 × 12) = √746496 = 864 cm².
(Check: it is a right triangle, so Area = 1/2 × 36 × 48 = 864 cm².)

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