释义 |
Triangle Inscribing in a CircleSelect three points at random on a unit Circle. Find the distribution of possible areas. The first point can beassigned coordinates (1, 0) without loss of generality. Call the central angles from the first point to the second andthird and . The range of can be restricted to [0, ] because of symmetry, but can range from . Then
| (1) |
so
| (2) |
where
| (3) |
Therefore,
But Write (4) as
| (6) |
then
| (7) |
and
| (8) |
From (6),
so
| (10) |
Also,
so
| (12) |
Combining (10) and (12) gives
| (13) |
The Variance is
See also Point-Point Distance--1-D, Tetrahedron Inscribing
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