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Find the area of a triangle whose sides are 7 cm., 8 cm. and 9 cm.

A) 28.642 sq. cm.
B) 26.832 sq. cm.
C) 24.564 sq. cm.
D) 22.832 sq. cm.

Correct Answer:


B) 26.832 sq. cm.

Description for Correct answer:
Area of the triangle = \( \Large \sqrt{s \left(s-a\right) \left(s-b\right) \left(s-c\right) } \)

\( \Large s = \frac{a+b+c}{2} \)

\( \Large s = \frac{7+8+9}{2}=\frac{24}{2} \)= 12 cm.

Area of the triagle =\( \Large \sqrt{12 \left(12-7\right) \left(12-8\right) \left(12-9\right) } \)

=\( \Large \sqrt{12 \times 5 \times 4 \times 3} = \sqrt{36 \times 4 \times 5} = 6 \times 2\sqrt{5} \)

=\( \Large 6 \times 2.236=12 \times 2.236=26.832 sq. cm. \)

Part of solved Area and perimeter questions and answers : >> Elementary Mathematics >> Area and perimeter

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