Question

Find the area of the equalatral triangle side is 20 cm

Answer 1

area of equilateral triangle

$\frac{ \sqrt{3} }{4} {side}^{2}$

$\frac{ \sqrt{3} }{4} \times 20 \times 20$

$100 \sqrt{3} {cm}^{2}$

Answer 2

Find the area of the equalatral triangle side is 20 cm.

Soln :

As we are told that it's is an equilateral triangle . which means all sides of the triangle would be equal .

So let ABC be sides of the triangle .

Formula used = Heron's formula

$area \: of \: a \: triangle = \sqrt{s(s - a)(s - b)(s - c)} where \: s = \frac{a + b + c}{2} \\ \\ s = \frac{21}{2} = 10.5 \\ \\ area \: = \sqrt{(10.5)(10.5 -20)(10.5 - 20)(10.5 - 20) } \\ \\ area \: = \: \sqrt{(10.5)(9.50)(9.50)(9.50) \} } \\ \\ area \: = \sqrt{9002.4357 } \\ \\ area = \sqrt{94.8811756883}$