Question

find the area of an equilateral triangle whose perimeter is 80 cm​

Answer 1

Answer:

Perimeter= 80cm

Side=?

Perimeter of triangle =side +side+side

80 = s+s+s

80=3s

80/3=s

26.6=s

Area of triangle=√3/4(side×side)

                          = √3/4(26.6 × 26.6)

                           = √3/4×707.56

Answer 2

$\bold\red{\underline{\underline {Answer:}}}$

$307.77 {cm}^{2}$

$\bold\red{\underline{\underline {Step-by-step \: explanation:}}}$

Here, we are given,

▪Perimeter of a triangle = 80 cm

Hence, The sum of the three side of a triangle is = 80 cm

∴ The 1 side of the triangle is = $\frac {80}{3}$

$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:$=26.66 cm

$The \: area \: of \: the \: triangle \: is = \frac{ \sqrt{3} }{4} {a}^{2} \\ Here, \: a = 26.66 \: cm \\ ∴area = \frac{ \sqrt{3} }{4} \times (26.66)^{2} \\ \:\:\:\:\:\:\:\:\:\:\:\:\:\:= \frac{ \sqrt{3} }{4} \times 710.7556 \\ \:\:\:\:\:\:\:\:\:\:\:\:\:\:\:=sqrt{3} \times 177.6889 \\ \:\:\:\:\:\:\:\:\:\:\:\:\:\:\: = 307.77 \: {cm}^{2}$

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