(1)(x-√3/4)²+(y-1/4)²=1/4 (2)ρ=2√(2+2cosθ) (3)B
(1)
令
x=ρcosθ=sin(θ+π/3)cosθ
y=ρsinθ=sin(θ+π/3)sinθ
对x,y分别积化和差有:
x=1/2*[sin(2θ+π/3)+sin(π/3)]=1/2*[sin(2θ+π/3)+√3/2]
y=1/2*[cos(π/3)-cos(2θ+π/3)]
移项整理有:
2x-√3/2=sin(2θ+π/3)
2y-1/2=cos(2θ+π/3)
故(2x-√3/2)²+(2y-1/2)²=1整理即有:
(x-√3/4)²+(y-1/4)²=1/4
(2)原方程可划为:(x-2)²+y²=4
可令:x=2+2cosθ,y=2sinθ,
则由:ρ=√(x²+y²)=√(4x)=2√(2+2cosθ)
(3)由ρcosθ=2可知:x=ρcosθ=2,与θ=π/4对称,即求反函数,
x=2 的反函数为y=2,计算一下可知答案为B