P&C Challenge 4

There are n concurrent lines and another line parallel to one of them.Find the number of different triangles that will be formed by the (n+1) lines..

3 Answers

Chose any 2 concurrent lines .. you will get one triangle...

the answer should be nC2

No bhaiya according to d book they say ^n-1C₂

from the n concurrent lines the line which is parallel to our excluded line won't be counted as we cannot form a triangle with two parallel lines

by fixing the seprate non-concurrent line. as three concurrent lines cannot form a triangle .

we have to select 2 line from the rest (n-1) concurrent lines.

^n-1C₂

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