## Ellipse Graphs

0
5
10
-5
-10
0
5
10
-5
–  o  +  ←  ↓  ↑  →
F1
F2
P

PF1 = 11
PF2 = 5

PF1 + PF2 = 16

Click the P point and drag to change.

You can move the graph up-down, left-right if you hold down the "Shift" key and then drag the graph.

You can use this to investigate the property that Length PF1 + Length PF2 is constant for a particular ellipse. In this example, PF1 + PF2 = 16.

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