What is the number of diagonals in a polygon with n sides?
A
n(n-1)/2
B
n(n-3)/2
C
n(n+1)/2
D
nĀ²/2
Correct Answer: Option B ā n(n-3)/2
Explanation:
Diagonals = n(n-3)/2. A pentagon (n=5) has 5Ć2/2 = 5 diagonals. This formula comes from selecting 2 vertices from n vertices (C(n 2)) then s...
Diagonals = n(n-3)/2. A pentagon (n=5) has 5Ć2/2 = 5 diagonals. This formula comes from selecting 2 vertices from n vertices (C(n 2)) then subtracting n sides. Polygon formulas for diagonals interior angles and exterior angles are standard geometry topics tested in higher competitive exam papers.