The Book of Lemmas: Proposition 11
If two chords in a circle, AB and CD, intersect at right angles in a point O, not being the center, then:
AO2 + BO2 + CO2 + DO2 = diameter2.
Click on the plot to create points A and B on the circle's perimeter. Adjust the slider to move the x-coordinate, xO , of the point O, where the two lines intersect. Note that the sum of the squares of distances between points A, B, C and D is equal to the square of the diameter of the circle.
r AO2 + BO2 + CO2 + DO2 = diameter2
Download Help Document
What kind of issue would you like to report? (Optional)