Answer:
b = sqrt(3) sqrt(v/h) or b = -sqrt(3) sqrt(v/h)
Explanation:
Solve for b: 
v = (b^2 h)/3 
 
v = (b^2 h)/3 is equivalent to (b^2 h)/3 = v: 
(b^2 h)/3 = v 
 
Divide both sides by h/3: 
b^2 = (3 v)/h 
 
Take the square root of both sides: 
Answer: b = sqrt(3) sqrt(v/h) or b = -sqrt(3) sqrt(v/h)