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A triangle has two equal sides of 13 cm each and third side of 10 cm. The area (in cm2) of the triangle is:
Question

A triangle has two equal sides of 13 cm each and third side of 10 cm. The area (in cm2) of the triangle is:

A.

60

B.

45

C.

40

D.

50

Correct option is A

Given:

Two equal sides = 13 cm each

Third side = 10 cm

Formula Used:
Semi-perimeter (s) of the triangle:

s=a+b+c2 = \frac{a + b + c}{2}

where a, b, and c are the lengths of the sides.

The area A is then:

A = s(sa)(sb)(sc)\sqrt{s(s - a)(s - b)(s - c)}

Solution:

Semi-perimeter s:

s =13+13+102=362=18 cm= \frac{13 + 13 + 10}{2} = \frac{36}{2} = 18 \text{ cm}

Area:

A =18×(1813)×(1813)×(1810) \sqrt{18 \times (18 - 13) \times (18 - 13) \times (18 - 10)}

A =18×5×5×8= \sqrt{18 \times 5 \times 5 \times 8}

=18×25×8=3600=60 cm2= \sqrt{18 \times 25 \times 8} = \sqrt{3600} = 60 \text{ cm}^2

The area of the triangle is 60 cm².

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