POLYGONS and DIAGONALS

The following are characteristics of a polygon, EXCEPT

• It is a closed figure.

• It is two-dimensional or flat.

• It has a curve side.

• It has three parts which are sides, vertices, and angles.

Which of the following is a polygon?

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Which of the following is a convex polygon?

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Which of the following is a concave polygon?

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What is the name of a polygon that has 12 sides?

• decagon

• dodecagon

• nonagon

• undecagon

How many sides are there in a heptagon?

• 5

• 6

• 7

• 8

What is the name of the segment that connects two nonconsecutive vertices of a polygon?

• Angle

• Diagonal

• Side

• Vertices

What is the formula of finding the number of diagonals in a polygon?

• $\frac{n\left(n-1\right)}{2}$

• $\frac{n\left(n-2\right)}{2}$

• $\frac{n\left(n-3\right)}{2}$

• $\frac{n\left(n-4\right)}{2}$

How many diagonals are there in a polygon that has 20 sides?

• 100

• 170

• 200

• 270

What polygon has no diagonals?

• Decagon

• Nonagon

• Quadrilateral

• Triangle