In triangle PQR, PQ = 6 cm, PR = 8 cm, and QR = 12 cm. Calculate the area of the triangle PQR ?



In triangle PQR, PQ = 6 cm, PR = 8 cm, and QR = 12 cm. Calculate the area of the triangle PQR ?

A. 23.33 cm2

B. 17.5 cm2

C. 21.33 cm2

D. 28.67 cm2

Answer : C. 21.33 cm2


Explanation:

    In triangle PQR, by using heron's formula

    S = P + Q + R / 2

    S = 6 + 8 + 12 / 2

    = 26 / 2 = 13

    S = 13

    Area of the triangle PQR = sqrt ( S (S - P) * (S - Q) * (S - R) )

    = sqrt ( 13 (13 - 6) * (13 - 8) * (13 - 12) )

    = sqrt ( 455 )

    Area of the triangle PQR = 21.33 cm2

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