What’s the surface area of this octagonal prism? I really need help on this!
+23246 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 cm2 (approx)
To find the total area, we need two of the regular octagons (38.638 cm2), plus the 8 sides.
Each side has an area of 2 x 6.5 = 13 cm2.
Multiplying this by 8, we get 104 cm2
Final amount: (38.638 cm2) + (104 cm2) = 142.6 cm2
