The straight lines are arranged in an oblique formula y=2X+ 1, and it is concluded that K=2=tanX=2/ 1 is the opposite side of a right triangle, so it is written as the root number 5, so sinX=2 times the root number 5/5 and cosX= 5/5, because the fixed point is P( 1.

The parameter equation of a straight line is x= 1+ root number 5/5, y=3+2 times root number 5/5(t is the parameter).