Question

Tropic of cancer is at about 23.5° latitude and arctic circle is at 66.5° latitude.
a) How many percent of earth's surface area is between equator and tropic of cancer?
b) How many percent is north from the arctic circle?
c) Which latitude has the same amount of surface area north from it as the result from a) ?

Okay this is what i've done so far.
a) sin23.5° = h/6380km -> h = R*sin23.5° ≈ 2544km
1 - [(2*pi*6380*2544) / (pi*6380^2)] ≈ 20.25%
b) same idea = 6%

!! EDIT !!

Apparently my idea was right, but I was using circle's area equation instead of sphere area.

Answer 1

D for Daniel.

Answer 2

seems right to me

Answer 3

any ideas how to approach C?