Triangles

All the same, thank you!

If the perimeter is 120, then each side has to be 40. Using the 30-60-90 idea, if you split the triangle in half, then the base is 20 inches, and the height is 20•√3. Finally, if you use the formula 1/2•base•height, you get one half of the original to be 400•√3, and all of the original is800•√3 inches squared.

To Unknown Name

I follow everythng that you are doing until you say that one-half of the original is 400·sqrt(3).

Since the original base is 40 and the height is 20sqrt(3), isn't the original = (1/2)(40)(20sqrt(3)) = 400 sqrt(3)?