Respuesta :
The formula for lateral surface of a cylinder is:
SA = 2 *PI * r *h
Replace the letters with the given values:
400 = 2 * PI * r *40
Multiply the right side:
400 = r * 251.2
Divide both sides by 251.2:
r = 400 / 251.2
r = 1.59
The radius is 1.59 inches.