question_answer

On the sides AB, BC, CA of a \[\Delta ABC\], 3,4,5 district points (excluding vertices A,B,C) are respectally chosen. The number of triangles that can be constructed using these chosen points as vertices are

A)  220                                       

B)  215

C)  210                                       

D)  205

Correct Answer: D

Solution :

                             Number of triangles \[{{=}^{12}}{{C}_{3}}-(1{{+}^{4}}{{C}_{3}}{{+}^{5}}{{C}_{3}})\]