Determine the area of a triangle with sides of the following length: a = 19 m b = 20 m c = 21 m

Use Heron’s formula. The semiperimeter is (19 + 20 + 21) ÷ 2 = 30 m, so the area is √[30(30 − 19)(30 − 20)(30 − 21)] = √29,700 ≈ 172.3 m². The closest listed choice is 172 m².

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