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NDA2021MathematicsPermutation and CombinationActual

Suppose 20 distinct points are placed randomly on a circle. Which of the following statements is/are correct? 1. The number of straight lines that can be drawn by joining any two of these points is 380 . 2. The number of triangles that can be drawn by joining any three of these points is 1140 . Select the correct answer using the code given below.

Options

  1. A1 only
  2. B2 only
  3. CBoth 1 and 2
  4. DNeither 1 nor 2

Correct answer

B. 2 only

Step-by-step solution

Number of St lines = ²⁰ C ₂=190 Number of triangles = ²⁰ C ₃=1140

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