NDA2019MathematicsPermutation and CombinationActual
What is the number of diagonals of an octagon?
Options
- A48
- B40
- C28
- D20
Correct answer
D. 20
Step-by-step solution
aligned & Numbers of diagonals = ^n C₂-n & diagonals in octagon = ^8 C₂=-8 & = 8 7 2 -8 & =28-8=20 aligned