Question

Number of diagonals for a polygon of any number of sides greater than 3 is given by n(n-3)/2 .Write the number of diagonals in (i) Hexagon (ii) Heptagon (iii) octagon (iv) Decagon
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Answer 1

Answer:

Formula for finding diagonals in polygon= n(n-3) /2

(I) Hexagon

Since it is a 6 sided figure,the value of n will be 6

=6(6-3)/2

=6*3/2

=18/2

=9 diagonals

(ii) Heptagon

Heptagon is a 7 sided figure, the value of n will be 7

=7(7-3) /2

=7*4/2

=28/2

=14 diagonals

(iii) Octagon

octagon is a 8 sided figure, the value of n will be 8

=8(8-3)/2

=8*5/2

=40/2

=20 diagonals

(iv) Decagon

As it is a 10 sided figure, the value of n will be 10

=10(10-3) /2

=10*7/2

=70/2

=35 diagonals

Hope this helps :)