There are 12 points in a plane of which 5 are collinear. The number of triangles is

To find the number of triangles, we can use the combination formula.

Step 1: Determine the number of ways to choose 3 points from the 12 points in the plane. This can be calculated using the combination formula, which is given by:

C(n, r) = n! / (r!(n-r)!)

where n is the total number of points and r is the number of points we want to choose (in this case, 3).

Step 2: Calculate the number of ways to choose 3 points from the 5 collinear points. Since these points are collinear, they cannot form a triangle. Therefore, we need to subtract this number from the total number of ways to choose 3 points.

Step 3: Subtract the number of ways to choose 3 points from the collinear points from the total number of ways to choose 3 points.

Step 4: Simplify the expression to find the final answer, which will give us the number of triangles that can be formed using the given points.