Question 1036977: The number of circles that can be formed by using 7 non-collinear points are
(a) 35 (b) 21
(c) 28 (d) 1
Ans:-35
How???????? Answer by Alan3354(69443) (Show Source):
You can put this solution on YOUR website! The number of circles that can be formed by using 7 non-collinear points are [sic]
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Pick any 3 points to determine a circle.
The 1st is 1 of 7
then 1 of 6, then 5
--> 7*6*5 = 210
But points A, B & C is the same as B, A & C --> 3*2*1 = 6 ways to make the same choices.
210/6 = 35
