If there are nine straight lines of which five are concurrent at a point and the other four are concurrent at another point and no two of these nine lines are parallel, then the number of points of intersection is equal to

Step-by-step solution

Nine straight lines will intersect at C 2 9 points Five are concurrent at one point so there will be loss of C 2 5 points Four other are concurrent at another point, so there is further loss of C 2 4 points. But we will have these two points at which the lines are concurrect. So, total number of points = C 2 - C 2 5 - C 2 4 + 2 9 = 36 - 10 - 6 + 2 = 22