Rectangle - Length of Portion of Side - Solution/Explanation

1) "Produced" in geometry means extended. If a line AB is produced to P it is extended to P.

2) The little marks next to the letters in P' and R' (called prime symbols) are not being used as the symbol for feet. Primes are used to denote a multiple things e.g. P is a point P' is another point and P'' is yet another point. R is one rectangle and R' is another rectangle.

3) If P is a point, P' (pronounced "pee prime") is another alternative point P. They are used because the problem, is capable of 2 different solutions, one with a positive root and one with a negative root. P is used as one extension of AB (to the right) in one solution and P' is the alternative extension of AB (to the left) in the other solution. As the explanation says.

Thanks for the explanation.