#10.) If DB = 2x-4 and PB = 2x-9, find PD
PD = √[ (2x - 4)^2 + (2x - 9)^2 ] =
√ [ 4x^2 - 16x + 16 + 4x^2 - 36x + 81 ] =
√ [ 8x^2 - 52x + 97 ]
