+0  
 
0
51
1
avatar

The number of diagonals in a certain regular polygon is equal to two times the number of sides. How many sides does this polygon have?

 Dec 1, 2020
 #1
avatar+114592 
+1

Number of diagonals in a polygon is given by :

n ( n-3)  / 2    where n  = the number of  sides

 

So

 

n ( n- 3)  / 2  =   2n     simplify

 

n (n -3)  =  4n

 

n^2  - 3n  = 4n

 

n^2 - 7n  =  0

 

n ( n - 7)  =  0

 

Setting each  factor to 0  and solving for  n  produces   

 

n  = 0      reject

 

n =  7

 

 

cool cool cool

 Dec 2, 2020

60 Online Users

avatar
avatar
avatar