How many sides? :O
Geometry
Level
2
The perimeter of a regular polygon varies directly as the length of sides. There is a certain polygon with a perimeter of 720 cm. If the length of side is decreased by 40 cm, the perimeter is (1/3) less. How many sides is that polygon?
The answer is 6.
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We can call the number of sides: x and the length of the sides of the initial polygon with x sides: y . Then we can establish the system :
y 7 2 0 = x
x ( y − 4 0 ) = 4 8 0
Solving we get that x = 6 and y = 1 2 0