Exercise for 3 seconds, speed 1cm/s, and stop at point p. AP = 3cm, Pb = 3cm.
Q point motion ts, speed 2cm/s, ∴? BQ=2t? ,? QC= 12-2t
At RT△QBP and RT△DCQ,
QP? =BQ? +PB? =3? +(2t)? =9+4t? ,
QD? =DC? +CQ? =6? +( 12-2T)? =4t? -48t+ 180
∴9+4t=4t? -48t+ 180 is used to solve equations? t= 17 1/48=? 57/ 16? (s)