Question

find the
area of eavilateral triangle whose side is 18cm.​

Answer 1

Given:

Each side of an equilateral triangle is 18 cm

To find:

The area of the equilateral triangle

The formula to find the area of the equilateral triangle is

$\boxed{\red{\frac{\sqrt{3}}{4}(a)^{2}}}\ unit\ sq.$

[Where 'a' is the 'side' of the triangle]

Now putting the given value,

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

$Area = \frac{\sqrt{3}}{4}\times(18)\times(18)$

Area = √3 × 9 × 9

Area = 81√3 cm sq.

Solving it further by putting the value of √3

Area of the equilateral triangle = 81 × 1.732

= 140.29 cm sq.

Hence,

The area of an equilateral triangle is 81√3 cm sq. (approximately 140.29 cm  sq.)

Answer 2

Answer:

Given:-

Find the area of equilateral triangle whose side is 18 cm.

To Find:-

The area of equilateral triangle.

Note:-

●》Area of equilateral triangle = √¾ ( a )². Here, "a" is side.

●》Square of a number ( number² ) means a number is multiplied with its same number and under root value should be classified first.

●》When units are multiplied then they will be in unit square, for example = cm × cm is always = cm².

Solution:-

Side = 18 cm, Area = ?

☆ According to note first point { Area = √¾ ( a )² }~

▪︎$Area \ \ of \ \ an \ \ equilateral \ \ triangle = √¾ ( 18 cm )²$

▪︎$Area \ \ of \ \ an \ \ equilateral \ \ triangle = √¾ × 18 cm²$

☆ After doing some calculations~

▪︎$Area \ \ of \ \ an \ \ equilateral \ \ triangle = √3 × 9 cm × 9 cm$

▪︎$Area \ \ of \ \ an \ \ equilateral \ \ triangle = 81√3$

☆ According to note second point~

▪︎$Area \ \ of \ \ an \ \ equilateral \ \ triangle = 81 × 1.732$

☆ After doing calculations and accordingly to note third point~

▪︎$Area \ \ of \ \ an \ \ equilateral \ \ triangle = 140.29 cm²$

Answer:-

The area of an equilateral triangle = 140.29 cm² ( by approximation ).