If four lines intersect in a plane, at the maximum how many triangles are formed?

If two lines are intersected by a transversal, then how many pairs of interior angles are formed?

If two lines are intersected by a transversal then how many pairs of alternate angles are formed?

Consider 12 points on a plane of which five are collinear. How many triangles can be formed using the 12 points?

out of 18 points in a plane no three are in the same straight lines except five points which are collinear how many triangles can be formed by joining them?

Intersection of a line and plane

If two parallel lines are intersected by a transversal then how many pairs of corresponding angles are formed?