Question

How many different straight lines can be formed by joining 12 different points on a plane of which 4 are collinear and the rest are non-collinear?

Answer 1

Answer:

12

Step-by-step explanation:

No. of points =12

To draw a line two points are required.

If no three points are collinear then the no. of lines = 12C2

Since 5 points are collinear, using these 5 points we can draw only one line.

∴ The no. of different lines =12C2−5C2+1 (single line using collinear points)

=66−10+1=57