A corner is removed from a rectangle. The rectangle measures 20 cm by 10 cm.[br][br]The right triangle that is removed measures (a+1) cm by (a-1) cm as shown on the diagram.[br][br]The shape that remains is a pentagon.[br][br]The perimeter of the pentagon depends on the value of a.

Determine and simplify the function for P, the perimeter of the pentagon in terms of a.[br][br]Type your function into the graphing applet below.[br][br]Compare the test point on the function to the values of perimeter in the applet above to validate your calculation.