To go from v_1 to v_2 the x coordinate decreased by 7 and the y coordinate decreased by 20.
To go from v_1 to the center (h, k), the x coordinate must decrease by 3.5 and the y coordinate must decrease by 10:
Therefore, h = 1.5, k = 0, and the center of the ellipse is (1.5, 0)
The length of the semi-major axis, a, is the distance from the center to either vertex:
a = sqrt((5 - 1.5)^2 + (10 - 0)^2)
a = sqrt((3.5)^2 + 10^2)
a = sqrt(449)/2
Let A = the angle of rotation, then:
sin(A) = 10/(sqrt(449)/2), and cos(A) = 3.5/(sqrt(449)/2)
Rationalizing both denominators:
sin(A) = (20sqrt(449))/449 and cos(A) = (7sqrt(449))/449
Here is a reference for An Rotated Ellipse that I not at the origin
((x - h)cos(A) + (y - k)sin(A))^2/a^2 + ((x - h)sin(A) - (y - k)cos(A))^2/b^2 = 1
Solving for b
1 - ((x - h)cos(A) + (y - k)sin(A))^2/a^2= ((x - h)sin(A) - (y - k)cos(A))^2/b^2
b^2 = (a^2((x - h)sin(A) - (y - k)cos(A))^2)/(a^2 - ((x - h)cos(A) + (y - k)sin(A))^2)
b = sqrt((a^2((x - h)sin(A) - (y - k)cos(A))^2)/(a^2 - ((x - h)cos(A) + (y - k)sin(A))^2))
Force this to contain the point (-5, -4):
b = sqrt(((449/4)((-5 - 1.5)(20sqrt(449))/449 - (-4 - 0)(7sqrt(449))/449)^2)/((449/4) - ((-5 - 1.5)(7sqrt(449))/449 + (-4 - 0)(20sqrt(449))/449)^2))
I used WolframAlpha to do the evaluation:
b = 5.80553
Here is the final equation:
((x - 1.5)(20sqrt(449))/449 + (y - 0)(7sqrt(449))/449)^2/(sqrt(449)/2)^2 + ((x - 1.5)(7sqrt(449))/449 - (y - 0)(20sqrt(449))/449)^2/(5.80553)^2 = 1
Here is a graph to prove it:
Desmos.com
