Question

The area of a regular octagon is 35 cm2. What is the area of a regular octagon with sides five times as long?
A. 625 cm2

B. 875 cm2

C. 175 cm2

D. 245 cm2

Answer 1

do i mulitply 35cm^2 * 5?

Answer 2

Bc i got C last time and it was incorrect :/

Answer 3

area of a octagon = 2*(1+sqrt(2))*S^2, with s=side
so, we have 35 = 2*(1+sqrt(2))*S^2 or
s^2 = 35/[(1+sqrt(2)]
now, to find area of a octagon if the sides be 5 times before
area = 2*(1+sqrt(2))*(5S)^2
= 2*(1+sqrt(2))*25S^2, subtitute s^2 to here
= 2*(1+sqrt(2))*25*35/[(1+sqrt(2)]
= 2*25*35
= 1750
lol, no answer in options

Answer 4

oh well , i guess i'll just take my best guess :) lol thanks

Answer 5

wait... looks i have mistaken above
35 = 2*(1+sqrt(2))*S^2 or
s^2 = 35/(2*[(1+sqrt(2)])
the new area = 2*(1+sqrt(2))*(5S)^2
= 2*(1+sqrt(2))*25*S^2
= 2*(1+sqrt(2))*25* 35/(2*[(1+sqrt(2)])
= 25*35
= 875

Answer 6

ohh okay understand ! unstead of multiplying 2*25*35 , you just multiply 25*35 , thanks so much!

Answer 7

i was leave 2's the first, forget 2/2 = 1
sorry.. :)

Answer 8

welcome