(x-1)²+(y+2)²=5令x=1+√5cosx则(y+2)²=5-5cos²x=5sin²xy=-2+√5sinxx-2y=-2√5sinx+√5cosx+4=-√[(2√5)²+(√5)²]]sin(x-z)+4=-5sin(x-z)+4其中tanz=√5/(2√5)=1/2所以-5+4...