The first time I tried this problem I made a mistake with isolating the variable. I needed to get the radius (r) on its own. The first time I attempted this problem I made a mistake by subtracting the 6 before I combined it with 1/3 since they are like terms. This gave me 12=1/3r^2 which is incorrect. The correct way to solve the solution is to combine 6 and 1/3 to get 2. Then after it is simple because you have 18=2r^2 so you just divide both sides by 2 and square it. This gave me the correct solution of r=3. The problem solving resources I used was I checked the back of the workbook since it gave a solution. I used that solution to help me identify my error and correct it. The concepts I used for this problem was isolating a variable, combining like-terms and radicals. Next time I encounter a challenging problem I will ask my group members or my teacher for help.