过点(2,-3)向圆(x-1)²+(y+3)²=1引切线,求切线方程
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![过点(2,-3)向圆(x-1)²+(y+3)²=1引切线,求切线方程](/uploads/image/z/2539766-38-6.jpg?t=%E8%BF%87%E7%82%B9%282%2C-3%29%E5%90%91%E5%9C%86%28x-1%29%26%23178%3B%2B%28y%2B3%29%26%23178%3B%3D1%E5%BC%95%E5%88%87%E7%BA%BF%2C%E6%B1%82%E5%88%87%E7%BA%BF%E6%96%B9%E7%A8%8B)
过点(2,-3)向圆(x-1)²+(y+3)²=1引切线,求切线方程
过点(2,-3)向圆(x-1)²+(y+3)²=1引切线,求切线方程
过点(2,-3)向圆(x-1)²+(y+3)²=1引切线,求切线方程
设切线为k(y+3)=x-2
整理后x-ky-3k-2=0
因为相切,那么圆心(1,-3)到切线的距离为1
d=|1+3k-3k-2|/√(k^2+1)=1
解得k=0
所以切线方程为x=2