# Easy Permutation-Combination Solved QuestionAptitude Discussion

 Q. How many diagonals can be drawn in a pentagon?
 ✔ A. 5 ✖ B. 7 ✖ C. 8 ✖ D. 10

Solution:
Option(A) is correct

A pentagon has $5$ sides. We obtain the diagonals by joining the vertices in pairs.

Total number of sides and diagonals:

$= {^5C_2}$

$= \dfrac{5×4}{2×1}$

$= 5×2$

$= 10$

This includes its $5$ sides also.

⇒ Diagonals $= 10 - 5 = 5$

Hence the number of diagonals,

$= 10 - 5$

$= 5$