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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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