High-School Level Probability

Question

If 3 points are taken on a circle, what is the probability that the triangle formed by joining these points is an obtuse angled triangle?

Also, how are the points chosen? Independent and uniformly distributed? — Trevor Wilson, Sep 29 '13 at 16:58

Indranil Banerjee · Accepted Answer · 2013-09-29T17:34:02.140

0

Edited. Probability that they are on the same side of a diameter. If the points are a, b and c then by first choosing a , the probability that b and c are in the same side of the diagonal formed by a is (1/2)(1/2)= 1/4. Since a is chosen arbitrarily at first by symmetry this will be the case if we had chosen b or c first. Hence the probability is 3/4.

edited Sep 29 '13 at 17:34

answered Sep 29 '13 at 16:58

Indranil Banerjee

456

Could you explain how you get $1/4$? The answer to Manoj's linked duplicate question differs. – Trevor Wilson Sep 29 '13 at 17:01
Because it's not really a duplicate. – BruceET Mar 31 '15 at 18:24

High-School Level Probability

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