Does Rover have enough roaming room? How much roaming room does Rover have? You must answer both questions. Write an explanation of how you got your answer. (Details Below)

You have a regular hexagonal fenced area in your backyard. Rover, your dog, is tied with a 12-meter chain at one of the vertices of the regular hexagon. The perimeter of the fence is 78 meters. Your veterinarian recommends that Rover have at least 150 square meters of roaming room.

1 Answer
Jun 17, 2018

#color(blue)("Yes")#

#color(blue)("Area"~~150.7964474" units"^2)#

Explanation:

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This is a regular hexagon, so all sides are of equal length.

The perimeter of the hexagon is 78 metres, and it has 6 sides.

Each side is:

#78/6=13 " metres"#

The sum of the interior angles of a regular polygon is given by:

#108^@n-360^@#

Where #bbn# is the number of sides.

Sum of angles:

#180^@*6-360^@=720^@#

Each angle:

#(720^@)/6=120^@#

The length of chain is 12 metres.

From diagram:

#AC=AB+AD=12#150.7964474" units"^2

Since #AC< AE#

The chain describes an arc:

#hat(BCD)#

#/_BAD# is the angle subtended by this arc.

#/_BAD=120^@#

The area that Rover has to roam is the area of the sector:

#Ahat(BCD)#

We can find this area by using:

Area of a sector is:

#1/2r^2theta#

Where #theta# is the angle subtended by the arc measured in radians.

Convert #120^@# to radians:

#(120^@*pi)/(180^@)=(2pi)/3#

Our radius is #AC=12#

Area of sector:

#"Area"=1/2(AC)^2((2pi)/3)=1/2*144*(2pi)/3=48pi" units"^2#

This is approximately:

#48pi~~150.7964474" units"^2#

This is greater than the recommended area of #150m^2#, so the answer is yes, Rover does have enough room to roam.