Hi. My problem is:
How many planes are determined by four points, no three of
which are collinear?
Thanks a lot!
Three noncolinear points determine a plane.
If the points are A, B, C, and D.
1. The three non-colinear points A, B, and C determine a plane.
2. The three non-colinear points A, B, and D determine a plane.
3. The three non-colinear points A, C, and D determine a plane.
4. The three non-colinear points B, C, and D determine a plane.
The answer is four.
You can also do it by the combination of 4 things taken 3 at a time
4C3
and using the formula
n!
nCr = ——————————
r!(n - r)!
4!
4C3 = ——————————
3!(4 - 3)!
4·3·2·1
4C3 = ——————————
3·2·1·(1)!
4·3·2·1
4C3 = ——————————
3·2·1
4C3 = 4
Edwin
AnlytcPhil@aol.com
