As shown in the figure, O is the center of the circle. Let it be the isosceles right angle of OH ⊥ DE and COH, CO = OH, ACO = ∠ OHB = 135? ，AO=BO=R

∴⊿ ACO ≌⊿ BHO ∴ The butt of an obtuse triangle is equivalent to the hypotenuse and waist of a right triangle? ∴∠CAO=∠CBO，

∠BOE=45？ +∞CBO

∠AOD=45？ -Cao

∴∠BOE+∠AOD=90？

∠AOE=90？ -∠AOD =∠ Dao,? Ao = bo again? ⊿AOD≌⊿OBE﹙AAS﹚∴OE=AD

The sum of the areas of two squares = ad? +BE？ =OE？ +BE？ =OB？ =R？

Is the sum of the areas of two squares a constant r? Of course, it can also be said that the maximum value is r? ﹚