tangent vertical <==> dx/dy = 0
tangent horizontal <==> dy/dx = 0
英语数学题求解~~~如图
tangent vertical <==> dx/dy = 0
tangent horizontal <==> dy/dx = 0
tangent vertical <==> dx/dy = 0
tangent horizontal <==> dy/dx = 0
tangent vertical <==> dx/dy = 0
tangent horizontal <==> dy/dx = 0