How do you work out the area of an equilateral triangle with sides of length 6cm? How do you work out the area of an equilateral triangle with sides of length 6cm?

1 Answer
Dec 1, 2015

9sqrt3" cm"^293 cm2

Explanation:

![http://jwilson.coe.uga.edu](https://useruploads.socratic.org/OVQ7ejRRq642nFyeGphv_kls1.jpg)

We can see that if we split an equilateral triangle in half, we are left with two congruent equilateral triangles. Thus, one of the legs of the triangle is 1/2s12s, and the hypotenuse is ss. We can use the Pythagorean Theorem or the properties of 30˚-60˚-90˚ triangles to determine that the height of the triangle is sqrt3/2s.

If we want to determine the area of the entire triangle, we know that A=1/2bh. We also know that the base is s and the height is sqrt3/2s, so we can plug those in to the area equation to see the following for an equilateral triangle:

A=1/2bh=>1/2(s)(sqrt3/2s)=(s^2sqrt3)/4

Thus, since s=6" cm", the area is (6^2sqrt3)/4" cm"^2 or 9sqrt3" cm"^2.