Explanation:
use the law of sine :
a/sin(A) = b/sin(B) = c/sin(C)
and therefore also
sin(A)/a = sin(B)/b = sin(C)/c
where the lines and corresponding angles are always opposite of each other.
and remember, the sum of all angles in a triangle is always 180°.
and sin(x) = sin(180-x).
so, we have
sin(32)/43 = sin(B)/53
sin(B) = 53×sin(32)/43 = 0.653156302...
B = 40.77999844...° ≈ 41°
C = 180 - 32 - 40.77999844... = 107.2200016...° ≈ 107°
43/sin(32) = c/sin(107.2200016...)
c = 43×sin(107.2200016...)/sin(32) = 77.507143... ft
≈ 78 ft
B' = 180 - B = 139.2200016...° ≈ 139°
C' = 180 - 32 - 139.2200016... = 8.779998438...° ≈ 9°
43/sin(32) = c'/sin(8.779998438...)
c' = 43×sin(8.779998438...)/sin(32) = 12.38595519... ft
≈ 12 ft