Question

Q. If there are 12 persons in a party and if each two of them shake hands with each other. How many handshakes happen in the party?

Q. There are 10 points in a plane , three of which are in the same straight line excepting 4 points , which are collinear. Find the (i) number of straight lines obtained from the pairs of these points (ii) number of triangles that can be formed with the vertices as these points.
Q. IF three consecutive co-efficient in the expansion of (1+x) ? are in the ratio 6:33:110. Find n and r.

Answer 1

que 1 : 12×2-10
answer : 14