答:
点P是椭圆4x^2+y^2=4即x^2+(y^2)/4=1上的动点
设x=cost,y=2sint,点M(0,1),则:
|PM|^2=(cost-0)^2+(2sint-1)^2
=(cost)^2+4(sint)^2-4sint+1
=3(sint)^2-4sint+2
=3(sint-2/3)^2+2/3
sint=2/3时|PM|^2取得最小值2/3,|PM|最小值√6/3
sint=-1时|PM|^2取得最大值3+4+2=9,|PM|最大值3
答:
点P是椭圆4x^2+y^2=4即x^2+(y^2)/4=1上的动点
设x=cost,y=2sint,点M(0,1),则:
|PM|^2=(cost-0)^2+(2sint-1)^2
=(cost)^2+4(sint)^2-4sint+1
=3(sint)^2-4sint+2
=3(sint-2/3)^2+2/3
sint=2/3时|PM|^2取得最小值2/3,|PM|最小值√6/3
sint=-1时|PM|^2取得最大值3+4+2=9,|PM|最大值3