use heron's formula for triangular area to derive the area of an equilateral triangle with side length x.
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A=

Step-by-step explanation:

Firstly, let's take the Heron's formula, which allows us to calculate the area of any triangle without the need of knowing the value of the height or the angle. Just the half of perimeter, and each side of a triangle.

A =

p = Semi perimeter  (Half of Perimeter)

2p =Perimeter (sum of all the values)

Keep in mind, that in an equilateral angle all of the sides have the same value, so to make things easy let's call, a, b and c just by one variable l

2) Replacing it in Heron's Formula:

The semiperimeter of an Equilateral Triangle is

P = =

3) Inserting all of that in the Heron's Formula

Finally we can derive the Equilateral Triangle Area  through Heron's:

-3

step-by-step explanation:

a drawing really does here:

so i draw the horizontal line y=2 and the vertical line x=-2 at this intersection i put b (this is where my right angle is going to be).   so point b is at (-2,2).   point a is 5 units long and is also on y=2 so this point has to be (3,2) or (-7,2) -doesn't matter i will go with (3,2).

now we know c is at (-2,y) we don't know the y yet bet we know that c is on x=-2.

we have the area of the triangle is .5bh=12.5

we know the base length is 5 (ab)

we have the height is (2-y) if you look at your

plug in

.5(5)(2-y)=12.5

solve for y to get the y-coordinate for c

2.5(2-y)=12.5

divide both sides by 2.5 giving:

2-y=5

now subtract 2 on both sides

-y=3

y=-3