Question

Ten points are marked on a straight line and eleven points are marked on another straight line. How many triangles can be constructed with vertices from among the above points?

• A. 495
• B. 550
• C. 1045
• D. 2475

Answer 1

Answer: (C)

1045

Answer 2

A triangle can be formed by taking any two points of a straight line and third point on the second straight line
$\rightarrow$Number of ways =$(C\frac{10}{2}\times 11)+(C\frac{11}{2}\times 10)$
$\rightarrow 495+550=1045$
The correct answer is (C) : 1045