Question

A.
10.8 square inches
B.
12.5 square inches
C.
21.7 square inches
D.
97.4 square inches

https://media.edgenuity.com/evresources/2091128_cdd0342c-8ba2-4b6b-9a70-a3a8a3c2be63.png

Find the area of the triangle, given that it has a perimeter of 15 inches. Round the answer to the nearest tenth.

Answer 1

whats the height

Answer 2

Well it's an equilateral triangle, so all the sides are the same length. Try dividing the perimeter by three first.

Answer 3

its B 12.5

Answer 4

if it is right give me a medal

Answer 5

@diamond2.0 Why don't you try explaining why? Otherwise nobody learns anything.

Answer 6

P= a+b+c
So if the perimeter of the triangle is 15 and the triangle is equilateral, then you would use the following formula to find the length of one side:
a= 15/3 (which is obviously 5)

Now, To find the area of the triangle, use the following formula:

Since you don't have the height, which is required to find the area of a tringle, you must plug in your answers until you get it right. In this case, depressingly enough, the answer has already been given. On the bright side, that give you good practice and you don't have to waste your time trying to plug in all the formulas. So here is what your work should look like:
First, you must find the height of the object, and since you already have the answer no thanks to *cough, cough, @diamond2.0, cough, cough*.
A= (1/2)bh
12.5= (1/2)5h
12.5= 2.5h
(12.5/2.5)= (2.5/2.5)h

5= h

So now you can pretend like you don't already know the answer and solve the problem...

A= (1/2)bh
A= (1/2)(5)(5)
A= (1/2)25

A= 12.5

Answer 7

Thanks @kgmarie :)