How many triangles can be formed in a decagon ?

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

How many triangles can be formed by joining the angular points of a decagon ? How many diagonals will it have ?

How many triangles can be formed by joining 6 points lying on a circle ?

How many triangles can be formed by joining the vertices of a hexagon?

How many triangles can be formed by joining the vertices of a hexagon?

How many triangles can be formed by joining the vertices of an n- sided polygen?

How many triangles can be formed by joining the vertices of a hexagon? How many diagonals are there for hexagon?

How many triangles can be formed by joining 15 points on the plane, in which no line joining any three points?

How many triangles can be formed by joining 15 points on the plane , in which no line joining any three points ?