How many sides does a Decagon have?A7B8C9D10

Dear student 

Decagon have 10 sides , and each angle is 144 degreee. 

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Chers 

Explanation: We know that to calculate number of diagonals in octagon is Number of diagonals is= n × (n -3)/2 27= n × (n -3)/2 n (n-3) = 54 n2– 3n = 54 n2– 3n-54 = 0 (n + 6) (n – 9)=0 n=-6 or n=9 So that we are calculating the sides it should be positive, therefore sides of polygon has 27 diagonals is 9