What is the area, in square inches, of a regular octagon with 9-inch sides if the distance from the center to any vertex is 10 inches?

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Answer 1 · 2016-10-07T09:29:18

#??#

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In a regular octagon, #x=360/8=45^@#
#=> a=2*r*sin(x/2)#

Given that #r=10# inches,
#=> a=2*10*sin22.5=7.65..# inches, not #9# inches as given.

The area of a regular Octagon can be found using the the following formula :

1) If #r# is given: #A=2sqrt2*r^2#

2) if #a# is given: #A=2(1+sqrt2)a^2#

Hope this helps.