NCERT Exemplar Solutions
Class 6 - Mathematics - Unit 2: Geometry - Multiple Choice QuestionsQuestion 2
Class 6 - Mathematics - Unit 2: Geometry - Multiple Choice Questions
Question. 2
The number of diagonals in a septagon is
(A)
21
(B)
42
(C)
7
(D)
14
Detailed Answer with Explanation:
Beginner-friendly steps:
-
Use the formula for the number of diagonals of an n-sided polygon:
\[ \\text{Diagonals} \\;=\\; \dfrac{n(n-3)}{2} \] -
A septagon has 7 sides. So put n = 7:
\[ n \\;=\\; 7 \] -
Find n − 3:
\[ n-3 \\;=\\; 7-3 \\;=\\; 4 \] -
Multiply n and (n − 3):
\[ n(n-3) \\;=\\; 7 \times 4 \\;=\\; 28 \] -
Divide by 2:
\[ \dfrac{28}{2} \\;=\\; 14 \]
Answer: 14 (Option D).