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Question

The sum of interior angles of a polygon is 2160°. The number of sides of the polygon is:

The correct answer is 14

Polygon Interior Angles Calculation

This problem asks us to determine the number of sides of a polygon given that the sum of its interior angles is \(2160^\circ\). To solve this, we will use the standard formula for the sum of interior angles of any polygon.

Polygon Angle Formula Explained

A polygon is a closed two-dimensional figure with straight sides. The interior angles are the angles formed inside the polygon by its adjacent sides. There is a well-known formula that relates the sum of these interior angles to the number of sides the polygon has.

The formula for the sum of the interior angles of a polygon with \(n\) sides is:

\[ \text{Sum of Interior Angles} = (n - 2) \times 180^\circ \]

Where \(n\) represents the number of sides of the polygon.

Sides Calculation Method

We are given that the sum of the interior angles of the polygon is \(2160^\circ\). We can use this information along with the formula to find the number of sides, \(n\).

  • Given: The sum of the interior angles \( = 2160^\circ \)
  • Formula to use: \( (n - 2) \times 180^\circ = \text{Sum of Interior Angles} \)

Let's substitute the given sum into the formula:

\[ (n - 2) \times 180^\circ = 2160^\circ \]

To find the value of \(n\), we first need to divide both sides of the equation by \(180^\circ\):

\[ n - 2 = \frac{2160^\circ}{180^\circ} \]

Performing the division:

\[ n - 2 = 12 \]

Now, to isolate \(n\), we add 2 to both sides of the equation:

\[ n = 12 + 2 \]

\[ n = 14 \]

Polygon Sides Result

Based on our calculations, the number of sides of the polygon with an interior angle sum of \(2160^\circ\) is 14. This type of polygon is known as a tetradecagon.

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Important Questions from Polygons

  1. What is the number of diagonals of an octagon?

  2. Consider a regular polygon with 10 sides. What is the number of triangles that can be formed by joining the vertices which have no common side with any of the sides of the polygon?

  3. What is the interior angle of a regular octagon of side length 2 cm?

  4. One angle of a pentagon is 140° and the remaining angles are in the ratio 1 : 2 : 3 : 4. The largest angle of the pentagon is equal to :

  5. Which is a more appropriate advantage of a histogram over a polygon?

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