由动点P引圆x2+y2=10的两条切线PA,PB...由动点P引圆x2+y2=10的两条切线PA,PB,直线PA,PB的斜率分别是k1,k2.(1) 若k1+k2+k1×k2=-1,求动点P的轨迹方程(2) 若点P在直线x+y=m上,且AP⊥BP,求实数m的取值范围.
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![由动点P引圆x2+y2=10的两条切线PA,PB...由动点P引圆x2+y2=10的两条切线PA,PB,直线PA,PB的斜率分别是k1,k2.(1) 若k1+k2+k1×k2=-1,求动点P的轨迹方程(2) 若点P在直线x+y=m上,且AP⊥BP,求实数m的取值范围.](/uploads/image/z/1765169-17-9.jpg?t=%E7%94%B1%E5%8A%A8%E7%82%B9P%E5%BC%95%E5%9C%86x2%2By2%3D10%E7%9A%84%E4%B8%A4%E6%9D%A1%E5%88%87%E7%BA%BFPA%2CPB...%E7%94%B1%E5%8A%A8%E7%82%B9P%E5%BC%95%E5%9C%86x2%2By2%3D10%E7%9A%84%E4%B8%A4%E6%9D%A1%E5%88%87%E7%BA%BFPA%2CPB%2C%E7%9B%B4%E7%BA%BFPA%2CPB%E7%9A%84%E6%96%9C%E7%8E%87%E5%88%86%E5%88%AB%E6%98%AFk1%2Ck2.%281%29+%E8%8B%A5k1%2Bk2%2Bk1%C3%97k2%3D-1%2C%E6%B1%82%E5%8A%A8%E7%82%B9P%E7%9A%84%E8%BD%A8%E8%BF%B9%E6%96%B9%E7%A8%8B%282%29+%E8%8B%A5%E7%82%B9P%E5%9C%A8%E7%9B%B4%E7%BA%BFx%2By%3Dm%E4%B8%8A%2C%E4%B8%94AP%E2%8A%A5BP%2C%E6%B1%82%E5%AE%9E%E6%95%B0m%E7%9A%84%E5%8F%96%E5%80%BC%E8%8C%83%E5%9B%B4.)
由动点P引圆x2+y2=10的两条切线PA,PB...由动点P引圆x2+y2=10的两条切线PA,PB,直线PA,PB的斜率分别是k1,k2.(1) 若k1+k2+k1×k2=-1,求动点P的轨迹方程(2) 若点P在直线x+y=m上,且AP⊥BP,求实数m的取值范围.
由动点P引圆x2+y2=10的两条切线PA,PB...
由动点P引圆x2+y2=10的两条切线PA,PB,直线PA,PB的斜率分别是k1,k2.
(1) 若k1+k2+k1×k2=-1,求动点P的轨迹方程
(2) 若点P在直线x+y=m上,且AP⊥BP,求实数m的取值范围.
由动点P引圆x2+y2=10的两条切线PA,PB...由动点P引圆x2+y2=10的两条切线PA,PB,直线PA,PB的斜率分别是k1,k2.(1) 若k1+k2+k1×k2=-1,求动点P的轨迹方程(2) 若点P在直线x+y=m上,且AP⊥BP,求实数m的取值范围.
1) 若k1+k2+k1×k2=-1,求动点P的轨迹方程
设点P为(a,b),
直线为y-b=k(x-a)
代入圆方程
x²+(kx-ak+b)²=10
(1+k²)x²-2kx(ak-b)+(ak-b)²-10=0
因直线与圆相切则方程仅有一实根
则4k²(ak-b)²=4(1+k²)[(ak-b)²-10]
a²k^4-2abk³+b²k²=a²k^4-2k³ab+k²(b²-10)+a²k²-2abk+b²-10
(a²-10)k²-2abk+b²-10=0
则k1+k2=2ab/(a²-10),k1*k2=(b²-10)/(a²-10)
因k1+k2+k1×k2=-1,
则2ab/(a²-10)+(b²-10)/(a²-10)=-1
2ab+a²-10+b²-10=0
(a+b)²=20
P点轨迹为x+y=±2√5两直线,除点(±√5,±√5)两个点以为.
2) 若点P在直线x+y=m上,且AP⊥BP,求实数m的取值范围
已证k1*k2=(b²-10)/(a²-10)
AP⊥BP
则k1*k2=-1
则(b²-10)/(a²-10)=-1
a²+b²=20
P点轨迹为x²+y²=20
有P在直线x+y=m上
则(m-y)²+y²-20=0
y²-my+m²/2-10=0
则m²>=4(m²/2-10)
m²
k1+k2+k1×k2=-1?????????