An = a1 + (n-1)*d
n = term to find = 30
a1 = first term = 20
d = common difference = 2
a30 = 20 + (30 - 1) * 2
a30 = 20 + 29 * 2
a30 = 20 + 58
a30 = 78
sn = (n (a1 + a30)) / 2
s30 = (30(20 + 78) / 2
s30 = (30(98) / 2
s30 = 2940/2
s30 = 1470 <===
946
Hope this helps o(*^▽^*)┛
BF is the radius for the circle.
