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📐 Mathematics  ·  Permutations and Combinations  ·  JEE

The number of triangles formed by 10 points (no 3 collinear):

Answer: 120.

  • A 90
  • B 120
  • C 210
  • D 720

Correct answer: B. 120

Explanation: Any 3 points form a triangle. 10C3 = 120.

StartABCBCACAB6 ordered outcomes (permutations); pairing AB/BA etc gives 3 combinations

Counting tree for selecting 2 items from {A, B, C} without repetition: 3 x 2 = 6 ordered arrangements.

Concept context

Counting, arrangements, and selections

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