1 You need to change A to B and B to A in the certificate, and nothing else will change.

2.

3. When the rectangular ABCD is square, the overlapping part is an isosceles right triangle.

An isosceles triangle with three internal angles acute cannot be obtained by this method.

4。 Let DF⊥OA be in F.

Because DE⊥OA of DF⊥OA.

So DE//DF

And because PD//OA

So DFEP is a parallelogram, so DF=PE.

Because DF⊥OA. So the triangle ODF is a right triangle.

Because ∠ AOB = 30, DF = 1/20d.

Because OD=6

So DF=3

So PE=3

If you agree with my answer, please click the adopt as satisfactory answer button in time?

Mobile phone questioners can evaluate "satisfaction" in the upper right corner of the client. ?

Your adoption is my motivation! ? Please ask me for help if you have any new questions. Not easy to answer. Thank you for your support. ...