Ellipse-set of points P such that the sum of the distances between P and two distinct fixed points, foci, is a constant. Horizontal equation: Vertical equation: b 2 +c 2 =a 2 Write equation in standard form and find foci: 4x 2 +25y 2 =100 (4x 2 /100)+(25y 2 /100)=1 (x 2 /25)+(y 2 /4)=1 (x 2 /5 2 )+(y...