<h3>
Answer: 80 meters</h3>
This is an isosceles triangle. The dashed line is the height which is perpendicular to the base 120. The height is always perpendicular to the base. The dashed line cuts the base into two equal pieces (this only works for isosceles triangles when you cut at the vertex like this).
So we have two smaller triangles each with a base of 60 and a height of x. Focus on one of the right triangles and use the pythagorean theorem to solve for x.
a^2 + b^2 = c^2
x^2 + (60)^2 = (100)^2
x^2 + 3600 = 10000
x^2 = 10000 - 3600
x^2 = 6400
x = sqrt(6400)
x = 80
Each smaller right triangle has side lengths of 60, 80, 100
Note the ratio 60:80:100 reduces to 3:4:5. A 3-4-5 right triangle is a very common pythagorean primitive.
There are 2 roots so the only way to complete the square is,
![y=2x^2+8x-9\\y=2[(x^2+4x)]-9\\y=2[(x^2+4x+4)-4]-9\\y=2[(x+2)^2-4]-9\\y=2(x+2)^2-8-9\\y=2(x+2)^2-17](https://tex.z-dn.net/?f=y%3D2x%5E2%2B8x-9%5C%5Cy%3D2%5B%28x%5E2%2B4x%29%5D-9%5C%5Cy%3D2%5B%28x%5E2%2B4x%2B4%29-4%5D-9%5C%5Cy%3D2%5B%28x%2B2%29%5E2-4%5D-9%5C%5Cy%3D2%28x%2B2%29%5E2-8-9%5C%5Cy%3D2%28x%2B2%29%5E2-17)
Just factor 2 out of 2x^2+8x (just ignore the -9) then find the number that will make the terms be able to complete the square.
then complete the square and multiply 2 inside the brackets.
subtraction as you already get the vertex form and know how to complete the square.
Vertex Form: 
Answer:
*insert answer*
Step-by-step explanation:
I dont know it but hey
:D
