Question

there are there are 20 non collinear points in a plane how many (¡)straight lines(¡¡) Triangles can be drawn by joining these points?

Answer 1

hi there !!
here is ur answer

formula to be used
n C r = n!/r!(n-r)!

no to straight lines can be drawn
= 20 C 2
and no of triangle can be drawn
= 20 C 3
hope helped...