20 1 1 Question 25 (3) of Mathematics in Tianjin Senior High School Entrance Examination asks how to answer, please write down the specific process.

If you rotate clockwise, as shown in the figure, point D is DE⊥OA in E, and point C is CF⊥OA in F.

∠∠AOD =∠ABO =β，

∴tan∠AOD= Germany /OE= 3/4,

Let DE=3x, OE=4x,

AE=3-4x，

In Rt△ADE, ad 2 = AE 2+de 2,

∴9=9x^2+(3-4x)^2，

∴x= 24/25，

∴D( 96/25，72/25)，

∴ The analytical formula of linear AD is: y= 24/7x- 72/7,

The straight line CD is perpendicular to the straight line AD and passes through the point d,

Let y=- 7/24x+b,

Then b=4,

The analytical formula of ∴ linear CD is y=- 7/24x+4.

If rotated clockwise, the analytical formula of straight CD can be obtained as y = 7/24x-4.

The analytical formula of ∴ linear CD is y=- 7/24x+4 or y = 7/24x-4.