Straight line and equation in senior one 1. The equation of the bisector of the angle between L1 and L2 is y = x, if the equation of L1 is Ax + by + C = 0 (AB > 0), then the equation of line L2 is A bx+ay+c=0 B ax-by+c=0 C bx+ay-c=0 D bx-ay+c=0

Straight line and equation in senior one 1. The equation of the bisector of the angle between L1 and L2 is y = x, if the equation of L1 is Ax + by + C = 0 (AB > 0), then the equation of line L2 is A bx+ay+c=0 B ax-by+c=0 C bx+ay-c=0 D bx-ay+c=0

Choose a
For multiple choice questions, special straight lines can be assumed,
For this problem, we can assume that the two lines are Y-axis and X-axis respectively, which is in line with the meaning of the problem
So choose a

1. It is known that the line L1: 2x + 3y-6 = 0 intersects the x-axis and the y-axis at points a and B respectively. Try to find a point P on the line L2: y = x, so that | PA | - | Pb |, and find the maximum value
2. Given the line L passing through point a (1,1) and the slope of - M (M > 0), the x-axis and y-axis intersect at points P, Q respectively, and make the vertical line 2x + y = 0 passing through point P and Q respectively, and the vertical feet are points R and S respectively, so as to find the minimum area of quadrilateral prsq
3. In order to green the city, a city plans to build a rectangular lawn in the rectangular ABCD, in which the triangular AEF area is a cultural relic protection area, which can not be occupied. According to the measurement, ab = 100m, BC = 80m, AE = 30m, AF = 20m. How should we design to make the lawn area the largest?
Now I only want to do the third question,

1.A(3,0)
B(0,2)
Do a point B with respect to the line y = x, symmetric point B '(2,0)
The point P (0,0) is obtained by connecting the intersection line y = x of ab 'to the point P (0,0)
In this case, | PA | - | Pb |, that is, the length of line ab '
We can go to any other point P 'on the line y = x, according to the fact that the difference between the two sides of the triangle is less than the third side
It can be seen that | p'a | - | p'b | is less than the length of line ab '
So, P is (0,0), and the maximum value is 1

High one mathematics straight line and equation formula?
Please tidy up!

Thank you