Question

how to find the area of an equilateral triangle with a side length of 10.4 meters

Answer 1

http://www.ezscrap.net/EquilateralTriangle_1000.gif

Bear this triangle in mind^.

The area of a triangle = 0.5bh
b=a=10.7 m
h=sqrt(a²-(0.5a)²)=sqrt(0.75a²)=sqrt(0.75*10.4²)=9.007
So:
Area=0.5bh=0.5*10.4*9.007=46.837 m²

Answer 2

area of an equilateral triangle = √ 3 / 4 ( a )^2
where a = side of the equilateral triangle
now you can say
area = √ 3 / 4 ( 10.4) ^ 2 = √ 3 / 4 x 10.4 x 10.4 =27.04√ 3

Answer 3

first find the heigh
10.4/2=5.2
\[\sqrt{10.4^{2}-5.2^{2}} =\sqrt{108.16-27.4}\]
the heigh is:\[\sqrt{80.76}\]
A=(b*h)/2
\[(10.4*\sqrt{80.76})\div 2\]

A= 46.730