求下列椭圆的长轴的短轴长，离心率，焦点坐标，顶点坐标:

1. x^2/16+y^2/4=1
a=4,b=2,c=2*3^(1/2)
e=c/a=[3^(1/2)]/2,
焦点：(2*3^(1/2),0),(-2*3^(1/2),0)
顶点坐标：(4,0),(-4,0),(0,2),(0,-2)

2. x^2/9+y^2/81=0
a=9,b=3,c=6*2^(1/2)
e=c/a=[2*2^(1/2)]/3
焦点：(0,6*2^(1/2)),：(0,-6*2^(1/2))
顶点：(3,0),(-3,0),(0,9),(0,-9)

a=4 b=2 c^2=a^2-b^2=12
焦点在x轴F(+_2*3^1/2,0)长轴顶点A(+_4,0)短轴顶点B(0,+_2)

a=9 b=3 c^2=a^2-b^2=72
焦点在y轴F(0,+_6*2^1/2)长轴顶点A(0,+_9)短轴顶点B(+_3,0)

椭圆 x^2/a^2+y^2/b^2=1 c^2=a^2-b^2 焦点在x轴 (a>b)

椭圆 x^2/b^2+y^2/a^2=1 c^2=a^2-b^2 焦点在y轴 (a>b)