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zhane2015

  • 3 years ago

The area of a regular octagon is 35 cm². What is the area of a regular octagon with sides three times as long? (1 point)315 cm² 175 cm² 225 cm² 105 cm²

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  1. zhane2015
    • 3 years ago
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    I just multiply the original area by 3 right??

  2. dave0616
    • 3 years ago
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    hmmm, im not sure if that is quite correct. personally i would find the sides of the octagon from the area equation and then redo the problem. Area of a octagon = side^2(2+2(sqrt(2))) 35cm^2=side^2(2+2(sqrt(2)) 35/(2+2(sqrt2)=side^2 7.25=side^2 sqrt(7.25)=side=2.69

  3. dave0616
    • 3 years ago
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    i would then multiply each side by 3 and plug that into the equation: 2.69*3=8.07 area=side^2(2+(2sqrt(2)) area=8.07^2(2+(2sqrt(2) area=315cm^2

  4. zhane2015
    • 3 years ago
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    Why multiply by 3?

  5. dave0616
    • 3 years ago
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    because each side is 3 times as long

  6. zhane2015
    • 3 years ago
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    ohhhh

  7. dave0616
    • 3 years ago
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    so that is why cant multiply the total area by 3, because it says that each side is 3times as long, not the total area is 3times as big

  8. zhane2015
    • 3 years ago
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    Oh ok...THANK YOU!!

  9. dave0616
    • 3 years ago
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    no problem

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