Question

An equilateral triangle has a perimeter of 48 cm. What is the area?

Answer 1

Answer:

$A=64\sqrt{3}\ cm^2$

Step-by-step explanation:

we know that

An equilateral triangle has three equal sides and three equal interior angles (each interior angle measure 60 degrees)

so

The perimeter is equal to

$P=3b$

where

b is the length side of the equilateral triangle

we have

$P=48\ cm$

substitute

$48=3b$

solve for b

$b=48/3\\b=16\ cm$

Find the area

The formula of area applying the law of sines is equal to

$A=\frac{1}{2}b^2sin(60^o)$

substitute the value of b

$A=\frac{1}{2}(16)^2sin(60^o)$

$sin(60^o)=\frac{\sqrt{3}}{2}$

$A=\frac{1}{2}(16)^2(\frac{\sqrt{3}}{2})$

$A=64\sqrt{3}\ cm^2$