This is tutorial on finding the points of intersection of an ellipse and a line given by their equations.
Example 1: Find the points of intersection of an ellipse and a line given by their equations as follows:
x2 / 9 + y2 / 4 = 1
y - 2x = -2
Solution to Example 1:
We first solve the equation of the line for y to obtain:
y = 2x - 2
We now substitute y by 2x - 2 in the equation of the ellipse
x2 / 9 + (2x - 2)2 / 4 = 1
Multiply all terms by 36, group like terms and rewrite the equation as
40x2 - 72x = 0
Solve the quadratic equation for x to obtain two solutions
x = 0 and x = 9/5
We now substitute the values of x already obtained into the equation y = 2x - 2 and find y
for x = 0, y = -2 and for x = 9/5, y = 8/5
There 2 points of intersection given by
( 0 , -2) and (9/5 , 8/5)
Shown below is the graph of the ellipse, the line and their points of intersection.
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