【求助】圆锥曲线-双曲线相关题,百度不到.

来源:学生作业帮助网 编辑:作业帮 时间:2024/10/01 08:50:06
【求助】圆锥曲线-双曲线相关题,百度不到.
xT[OA+nX:tKˋgf/]*REA_TPcbTL,N gf ⾜|;ߜ3R}xes}x }>y;~OэǑt-5|uD{{|͗EpjQP $hs[5Ƣ[UE|5WkKFޱvޭ̓kNu\6 Ǘ F0P&!_ vEG>*.2y&!=˷<ԭLC'",b8יʅh:b`#bXyڶt ‹ja3;;v.OF/G 5'ƐYvd)g8S(t7NJ)MCo+i6y52VI3{pAQQUL&*ZF QSu]϶|zq Og[&>'@gY:p@3%^#\qei>/F^Y

【求助】圆锥曲线-双曲线相关题,百度不到.
【求助】圆锥曲线-双曲线相关题,

百度不到.

【求助】圆锥曲线-双曲线相关题,百度不到.
(1)
设双曲线为x²/a² - y²/b² = 1
c = 2
a² + b² = c² = 4,b² = 4 - a²
x²/a² - y²/(4 - a²) = 1 (i)
切线:y - 0 = 2(x - 1/2),y = 2x - 1
代入(i)整理得:(4 - 5a²)x² + 4a²x + a²(a² - 5) = 0 (ii)
判别式∆ = (4a²)² - 4(4 - 5a²)a²(a² - 5) = 20a²(a⁴ - 5a² + 4) = 20a²(a² - 1)(a² - 4) = 0
a² = 1 (舍去a² = 0,a² = 4)
b² = 4 - 1 = 3
x² - y²/3 = 1
(2)
(ii)变为x² - 4x + 4 = (x - 2)² = 0
x = 2
P(2,3)
PF₁的方程:(y - 0)/(3 - 0) = (x + 2)/(2 + 2),3x - 4y + 6 = 0
PF₂的方程:x= 2,x - 2 = 0
Q与PF₁的距离d₁ = |3/2 -0 + 6|/√(3² + 4²) = 3/2
Q与PF₂的距离d₂ = 2 - 1/2 = 3/2
d₁ = d₂
PQ为角F₁PF₂的平分线