The answer is
round cake - 82.42 in²
rectangular cake - 114 in²
Round cake:
d = 7 in
r = d/2 = 7 in / 2 = 3.5 in
h = 2 in
The surface are of a cylinder is:
A = 2πr² + 2πrh
The surface are of the round cake (which is actually a cylindrical cake) excluding the bottom is:
A = 2πr² + 2πrh - πr²
A = πr² + 2πrh
A = 3.14 * 3.5² + 2 * 3.14 * 3.5 * 2
= 38.46 + 43.96
= 82.42 in²
Rectangular cake:
w = 6 in
l = 9 in
h = 2 in
The surface are of a rectangle is:
A = 2wl + 2wh + 2lh
The surface are of the rectangular cake excluding the bottom is:
A = 2wl + 2wh + 2lh - wl
A = wl + 2wh + 2lh
A = 6 * 9 + 2 * 6 * 2 + 2 * 9 * 2
= 54 + 24 + 36
= 114 in²
Step-by-step explanation: This answer is not mine but JcAlmighty’s so all credits go to them.
