Hello from MrBillDoesMath!
Answer:
The fourth choice, b = +\- sqrt( sg + a^2)
Discussion:
s = (b^2 - a^2)/g => multiply both sides by "g"
sg = b^2 - a^2 => add a^2 to both sides
sg + a^2 = b^2 => take the square root of each side
b = +\- sqrt( sg + a^2)
which is the fourth choice.
Thank you,
MrB
