x² + y² = 2(cos²t + sin²t) = 2
曲线C为以(0,0)为圆心,半径为√2的圆.
A(1,1),OA的斜率为1,切线l斜率为-1(与x轴的正半轴夹角为3π/4),方程为y - 1 = -(x - 1),y = 2 - x
l与x轴交于B(2,0)
在l上任取一点M(ρ,θ)
OM = ρ,OB = 2,∠BOM = θ,∠MBO = π - 3π/4 = π/4,∠BMO = 3π/4 - θ
按正弦定理:
OM/sin∠MBO = OB/sin∠BMO
ρ/sin(π/4) = 2/sin(3π/4 - θ)
ρ = √2/sin(3π/4 - θ)
以上回答你满意么?