Question

an isosceles triangle has perimeter 30cm and each of the equal sides is 12cm.find the area of a triangle
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Answer 1

$\large\sf{Perimeter=12+12+x}$

$\large\sf{30=24+x}$

$\large\sf{30-24=x}$

$\large\sf{x=6}$

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$\large\sf{s=\frac{30}{2}}$

$\large\sf{s=15}$

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$\large\sf{By\:Heron's\:Formula,}$

$\large\sf{\sqrt{s(s - a)(s - b)(s - c)}}$

$\large\sf{\sqrt{15(15 - 12)(15 - 12)(15 - 6)}}$

$\large\sf{\sqrt{3 \times 5 \times 3 \times 3 \times 9}}$

$\large\sf{\sqrt{3 \times 5 \times 3 \times 3 \times 3 \times 3}}$

$\large\sf{{9 \sqrt{15} cm}^{2}}$