4b. Laura has a 12-foot ladder. The safety instructions recommend the base of the ladder be placed 4 feet from the base of the wall. How highwill the ladder be able to reach on the wall? WRITE YOUR ANSWER AS A SIMPLIFIED RADICAL. (HINT: Use the abbreviation sqrt to mean "square root of." For example an answer might look like 5sqrt3, and be read "five times the square root of 3".)