# Find the Number of Sides in a Polygon If the Sum of Its Interior Angle Is: 1620° - Mathematics

Sum

Find the number of sides in a polygon if the sum of its interior angle is: 1620°

#### Solution

Let no. of sides = n

∴ Sum of angles of polygon = 1620°

∴ (2n - a) × 90° = 1620°

⇒ 2(n - 2) = (1620°)/(90°)

⇒ n - 2 = (1620°)/(2 xx 90°)

⇒ n - 2 = 9

⇒ n = 9 + 2

⇒ n = 11

Concept: Sum of Angles of a Polynomial
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#### APPEARS IN

Selina Concise Mathematics Class 8 ICSE
Chapter 16 Understanding Shapes
Exercise 16 (A) | Q 3.2 | Page 180
Selina Class 6 Mathematics
Chapter 28 Polygons
Exercise 28 (A) | Q 3.2
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