Find the area of an equilateral triangle having side 12 cm. [2 MARKS]

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Solution

Concept : 0.5 Mark
Application : 0.5 Mark
Calculation : 1 Mark

Since the triangle is equilateral, all the sides will be equal.

Therefore, semi perimeter of the triangle = $\frac{a + b + c}{2} = \frac{12 + 12 + 12}{2} = 18 c m$

Area of the triangle
= $\sqrt{s (s - a) (s - b) (s - c)} = \sqrt{18 (18 - 12) (18 - 12) (18 - 12)} = \sqrt{3888} = 62.35 c m^{2}$

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Find the area of an equilateral triangle having side 12 cm. [2 MARKS]

Concept : 0.5 Mark Application : 0.5 Mark Calculation : 1 Mark Since the triangle is equilateral, all the sides will be equal. Therefore, semi perimeter of the triangle = a+b+c2=12+12+122=18 cm Area of the triangle = √s(s−a)(s−b)(s−c)=√18(18−12)(18−12)(18−12)=√3888=62.35 cm2 ​