SOLUTION: Here is my problem: A piece of art is in the shape of an equilateral triangle with the sides of 7 in. Find the area of the piece of art. Round your answer to the nearest tenth.

Question 409603: Here is my problem:
A piece of art is in the shape of an equilateral triangle with the sides of 7 in. Find the area of the piece of art. Round your answer to the nearest tenth.
Answer by nerdybill(7384) (Show Source): You can put this solution on YOUR website!
A piece of art is in the shape of an equilateral triangle with the sides of 7 in. Find the area of the piece of art. Round your answer to the nearest tenth.
.
The challenge is to find the height. Draw a diagram--it'll help
.
Let h = height
then
h^2 + (7/2)^2 = 7^2
h^2 + 49/4 = 49
h^2 = 49 - 49/4
h^2 = 196/4 - 49/4
h^2 = 147/4
h = sqrt(147)/2
.
area then is
(1/2)base*height
(1/2)(7)(sqrt(147)/2)
(7/4)sqrt(147)
21.2 square inches

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