What’s the surface area of this octagonal prism? I really need help on this!

Guest Apr 19, 2020

#1**+1 **

I messed up the other answer because I found the volume, not the area.

There's a problem with the drawing. If this is a regular octagon and each edge is 2 cm, the diameter will be close to,

but not quite equal to, 4.5 cm.

There is a formula for the area of a regular octagon: Area = 2 · ( 1 + sqrt(2) ) · (edge)^{2}

When the edge = 2: Area = 2 · ( 1 + sqrt(2) ) · (2)^{2} = 8 · ( 1 + sqrt(2) ) = 19.314 cm^{2} (approx)

To find the total area, we need two of the regular octagons (38.638 cm^{2}), plus the 8 sides.

Each side has an area of 2 x 6.5 = 13 cm^{2}.

Multiplying this by 8, we get 104 cm^{2}

Final amount: (38.638 cm^{2}) + (104 cm^{2}) = 142.6 cm^{2}

geno3141 Apr 19, 2020