How do you calculate expanding double brackets.​

Kelsie wants to create a "SMART" goal to help her get to work on time every day. Which of the following is the best goal? O a) "I will stop being late for work by setting my alarm every day." O b) "I will get to work before 9 A.M. every day this month." Oc) "I will get to work on time." "I will get to work on or before 9 A.M. at least 20 workdays per month by O d) setting an alarm the night before and not hitting the snooze button."

Answer: r=4.5  feetexplanation: radius  r  is half of the diameter  d,⇒r=d2=92=4.5  feetidk i could be wrong

The length of what is left would be 1 1/2 feet long.