- the green
curve is an ellipse
- the two focii of the elipse are at
f and g
- the sum of the lengths of cf and cg is
always equal to the length of the major axis
- the tangent line shows the direction
of the ellipse's curvature at point c
- this tangent line creates two angles:
one angle with cf, and another angle with cg. These two opposing angles are
always equal to each other. This means that any ray of light that's emitted
from one focus point, if it reflects off the ellipse, will always intersect the
other focus point.
|
The