Question

find the area of an equilateral triangle whose perimeter is 45cm​

Answer 1

Answer:

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Step-by-step explanation:

First we have to find it's side so

= Perimeter = 45cm

= side = 3

so 45/3

= 15

Area of ∆ = side × side

= 15×15

= 225 Ans.

Answer 2

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Given:

A triangle whose perimeter is 45cm.

To find:

The area of an equilateral triangle.

Explanation:

We know that perimeter of triangle= 3 × side (3a)

→ 3a = 45cm

→ a = $\cancel{\frac{45}{3} }$

→ a = 15cm

Now,

We know that formula of the area of an equilateral Δ:

→ $\frac{\sqrt{3} }{4} a^{2}$      [sq. units]

Putting the value of a in above formula, we get;

→ $\frac{\sqrt{3} }{4} *(15)^{2}$

→ $\frac{\sqrt{3} *225}{4}$

→ $\frac{\sqrt{3} *\cancel{225}}{\cancel{4}}$

→ (√3 × 56.25)cm²

→ (1.732 × 56.25)cm²           [√3= 1.732]

→ 97.425cm²

Thus,

The area of an equilateral Δ is 97.43cm².      [approx]