From ∠AOD=β, Tan∠aod = Tan∠β ∠βis obtained.

So de: OE = 3: 4.

So let DE=x, we can find OE, AE=OA-OE. AE available

Given that AD=3, DE=X, AE can make equations according to Pythagorean theorem. Find x, and then the corresponding coordinates of point d will be known.

At the same time, point A and point D can be used to find the analytical formula of AD. According to AD⊥CD, (here, the vertical slopes of two straight lines are multiplied by-1, that is, k of y=kx+b is multiplied by-1. ), you can find the slope of the straight line CD (that is, k), and then substitute it into the coordinates of point D, that is, you can find the analytical expression of CD.

Look again, when rotating to a certain size, there is also a triangle in the third quadrant that is symmetrical with the triangle ACD found here. According to the nature of symmetry, you only need to multiply k and b of the analytical formula of CD found earlier by-1.

I don't know. Ask again. Do it yourself . I don't remember the answer.