Find the diameter
OA is 11
Find the diameter -GMATPREP
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thanks for the solution..swle24 wrote:since it is an equidrateral ABC length is 2/3 of its circumference. that means 2/3 πd=24 so d=36/π where π is 3.14 hence d=11
Is this based on some properties, haven't come across this before.
Is there something for an isoceles triangle as well?
No, the reason for it is based on the fact that a chord makes an angle at the centre that is double the one it makes on the circumference. So, the chord BC which makes 60º at circumference (point A) will make 120º at the centre. So the arc BC is making 120º at centre while arc BAC makes 240º.
Therefore, the arc length BAC is (240/360)*pi*d=24
Cheers
Therefore, the arc length BAC is (240/360)*pi*d=24
Cheers