Question 749246
Have a project with Angry Birds where you have to find the equation of a parabola for the bird's flight path in various situations. 
I have to pick a point at the origin and a point on the x axis for the pig to be placed and find the flight path (equation).
 How would i do this? I chose for points:
Bird placed at (0,0)
Pig placed at (5,0)
:
We need another point, 0,0 is of no use, lets choose 3,4 as a point
:
Using the form ax^2 + bx + c = y
We are using origin so we can ignore c, just find a and b
:
Write an equation for each point, find a and b
:
Point: 5,0
25a + 5b = 0
and
Point 3,4
9a + 3b = 4
:
Multiply the 1st equation by 3, the 2nd equation by 5
75a + 15b = 0
45a + 15b = 20
------------------subtraction eliminates b, find a
30a = -20
a = -20/30
a = -.67
Use the 1st equation to find b
25(-.67) + 5b = 0
-16.67 + 5b = =
5b = 16.67
b = 16.67/5
b = 3.33
:
The equation: y = -.67x^2 + 3.33x
looks like this
{{{ graph( 300, 200, -2, 8, -2, 6, -.67x^2+3.33x) }}}