已知sinα是方程5x²-7x-6= 0的根〔sin(-α-3/2π)sin(3/2π-α)*tan ^2(2π-α)〕/〔cos(π/2-α)cos(π/2 +α)
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![已知sinα是方程5x²-7x-6= 0的根〔sin(-α-3/2π)sin(3/2π-α)*tan ^2(2π-α)〕/〔cos(π/2-α)cos(π/2 +α)](/uploads/image/z/2520046-46-6.jpg?t=%E5%B7%B2%E7%9F%A5sin%CE%B1%E6%98%AF%E6%96%B9%E7%A8%8B5x%26%23178%3B-7x-6%3D+0%E7%9A%84%E6%A0%B9%E3%80%94sin%EF%BC%88-%CE%B1-3%2F2%CF%80%EF%BC%89sin%EF%BC%883%2F2%CF%80-%CE%B1%EF%BC%89%2Atan+%5E2%EF%BC%882%CF%80-%CE%B1%EF%BC%89%E3%80%95%2F%E3%80%94cos%EF%BC%88%CF%80%2F2-%CE%B1%EF%BC%89cos%EF%BC%88%CF%80%2F2+%2B%CE%B1%EF%BC%89)
已知sinα是方程5x²-7x-6= 0的根〔sin(-α-3/2π)sin(3/2π-α)*tan ^2(2π-α)〕/〔cos(π/2-α)cos(π/2 +α)
已知sinα是方程5x²-7x-6= 0的根
〔sin(-α-3/2π)sin(3/2π-α)*tan ^2(2π-α)〕/〔cos(π/2-α)cos(π/2 +α)
已知sinα是方程5x²-7x-6= 0的根〔sin(-α-3/2π)sin(3/2π-α)*tan ^2(2π-α)〕/〔cos(π/2-α)cos(π/2 +α)
5x²-7x-6=0
(5x+3)(x-2)=0
x=-3/5 x=2>1
取sinα=-3/5
cos(2π-α)cos(π+α)tan²(2π-α)/sin(π-α)sin(2π-α)cot(π-α)
=-cosαcosαtan²α/sinαsinαcotα
=-sinα/cosα=-sinα/[√(1-cosα²)]
=±(3/5)/(4/5)
=±3/5