11
ρcosθ+2ρsinθ=0可化为:
x+2y=0
{x=4cosα
{y=2sinα
可化为:
x^2/4^2+y^2/2^2=cos^2(α)+sin^2(α)=1
x^2/16+y^2/4=0
x^2=(-2y)^2=4y^2
4y^2/16+y^2/4=1
y^2/2=1
y^2=2
y1=√2 , y2= - √2
x1= - 2√2 , x2= 2√2
AB=√[(2√2+2√2)^2+(-√2-√2)^2]=√40=2√10
12
直观图是一个上面为圆锥,拿猛下面是等底圆柱;
S(柱侧)=(2π*1)*2=4π
S(圆唤余柱底)=π*1^2=π
在圆锥中
r=1
L=√2
S(锥消链桥侧)=π*r*L=√2π
S(全)=(5+√2)π