If #theta# is eliminated from the equation #x=acos(theta-alpha)# and #y=bcos(theta-beta)# then prove that #(x/a)^2+(y/b)^2-(2xy)/(ab)cos(alpha-beta)=sin^2(alpha-beta#)?
Inserting in LHS we get
I add here what I see in this family of ellipses given by the .second degree equation
I add here what I see in this 4-parameter family of ellipses.
The elimination of
interested readers to know more about these equations.
The second degree equation equation
represents a family of ellipses, bracing the rectangle
It represents the diagonals of the enveloping rectangle, with ends
as vertices of the rectangle.a straight line
Another form of the equation, without