How many diagonals a triangle have?

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A triangle has nine diagonals in it.

A triangle does not have any diagonal in it.

A triangle has four diagonals in it.

A triangle has three diagonals in it.

answer is D.

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Detailed Solution

We have to find the number of diagonals of a triangle.
A triangle is the polygon that contain 3 sides and whose sum of internal angles is equal to

180 °

Formula of number of diagonals in a polygon:

d = n n − 3 2

Where, n = number of sides of a polygon.
Identify the number of sides of the said polygon.
Number of sides in a triangle is 2.

⇒ d = 6 2 − 3 2 ⇒ − 3

Since, negative value of number of diagonals is not possible
Hence, a triangle does not have any diagonal in it.
Hence, the correct option is 4.

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