Best Answer

90.

Number of diagonals = number_of_sides × (number_of_sides - 3) ÷ 2

→ For a Pentadecagon which has 15 sides:

Number of diagonals = 15 × (15 - 3) ÷2 = 15 × 12 ÷ 2 = 90

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Q: How many diagonal lines does a pentadecagon have?

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it has 4 :)

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14.

A Pentadecagon had 15 sides

the answer would be 2

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