Question

Find the area of an equilateral triangle each of whose sides measures (i) $18cm$, (ii) $20cm$.
[Take $\sqrt{3}=1.73$]

Answer 1

(i)

Side of the equilateral triangle $=18cm$
Area of the equilateral triangle $=\frac{\sqrt{3}}{4}{\text{side}}^2$ sq.units

$=\frac{\sqrt{3}}{4}\times (18cm{)}^2$

$=\frac{\sqrt{3}}{4}\times 324c{m}^2$

$=81\sqrt{3}c{m}^2$

$=81\times \left(1.73\right)c{m}^2$ [$\because \sqrt{3}=1.73$]

$=140.13c{m}^2$

(ii)

Side of the equilateral triangle $=20cm$
Area of the equilateral triangle$=\frac{\sqrt{3}}{4}{\text{side}}^2$

$=\frac{\sqrt{3}}{4}\times (20cm{)}^2$

$=\frac{\sqrt{3}}{4}\times 400c{m}^2$

$=100\sqrt{3}c{m}^2$

$=100\times \left(1.73\right)c{m}^2$ [$\because \sqrt{3}=1.73$]

$=173c{m}^2$