诱导公式.1.已知cos31°=a,则sin239°tan149°=_____2.求三角函数值 (1)cos(-17π/4) (2)sin26π/3 (3)cos1650° (4)sin1740°3.[sin(180°-405°)sin(270°-765°)]/[sin(90°+45°)tan(270°+45°)]=______4.当角
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![诱导公式.1.已知cos31°=a,则sin239°tan149°=_____2.求三角函数值 (1)cos(-17π/4) (2)sin26π/3 (3)cos1650° (4)sin1740°3.[sin(180°-405°)sin(270°-765°)]/[sin(90°+45°)tan(270°+45°)]=______4.当角](/uploads/image/z/8412956-44-6.jpg?t=%E8%AF%B1%E5%AF%BC%E5%85%AC%E5%BC%8F.1.%E5%B7%B2%E7%9F%A5cos31%C2%B0%3Da%2C%E5%88%99sin239%C2%B0tan149%C2%B0%3D_____2.%E6%B1%82%E4%B8%89%E8%A7%92%E5%87%BD%E6%95%B0%E5%80%BC+%EF%BC%881%EF%BC%89cos%EF%BC%88-17%CF%80%2F4%EF%BC%89+%EF%BC%882%EF%BC%89sin26%CF%80%2F3+%EF%BC%883%EF%BC%89cos1650%C2%B0+%EF%BC%884%EF%BC%89sin1740%C2%B03.%5Bsin%EF%BC%88180%C2%B0-405%C2%B0%EF%BC%89sin%EF%BC%88270%C2%B0-765%C2%B0%EF%BC%89%5D%2F%5Bsin%EF%BC%8890%C2%B0%2B45%C2%B0%EF%BC%89tan%EF%BC%88270%C2%B0%2B45%C2%B0%EF%BC%89%5D%3D______4.%E5%BD%93%E8%A7%92)
诱导公式.1.已知cos31°=a,则sin239°tan149°=_____2.求三角函数值 (1)cos(-17π/4) (2)sin26π/3 (3)cos1650° (4)sin1740°3.[sin(180°-405°)sin(270°-765°)]/[sin(90°+45°)tan(270°+45°)]=______4.当角
诱导公式.
1.已知cos31°=a,则sin239°tan149°=_____
2.求三角函数值 (1)cos(-17π/4) (2)sin26π/3 (3)cos1650° (4)sin1740°
3.[sin(180°-405°)sin(270°-765°)]/[sin(90°+45°)tan(270°+45°)]=______
4.当角α,β满足的条件为_____,有sinα=sinβ
诱导公式.1.已知cos31°=a,则sin239°tan149°=_____2.求三角函数值 (1)cos(-17π/4) (2)sin26π/3 (3)cos1650° (4)sin1740°3.[sin(180°-405°)sin(270°-765°)]/[sin(90°+45°)tan(270°+45°)]=______4.当角
1) -(1-a^2) ½ -a/(1-a^2)½
2) 2½ /2 3½/2 -1/3½ 3½/2
3)-2½/2
4)α+β=?π(?=奇数)
先把那些角都化简
sin(-α) = -sinα
cos(-α) = cosα
tan (—a)=-tanα
sin(π/2-α) = cosα
cos(π/2-α) = sinα
sin(π/2+α) = cosα
cos(π/2+α) = -sinα
sin(π-α) = sinα
...
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先把那些角都化简
sin(-α) = -sinα
cos(-α) = cosα
tan (—a)=-tanα
sin(π/2-α) = cosα
cos(π/2-α) = sinα
sin(π/2+α) = cosα
cos(π/2+α) = -sinα
sin(π-α) = sinα
cos(π-α) = -cosα
sin(π+α) = -sinα
cos(π+α) = -cosα
tanA= sinA/cosA
tan(π/2+α)=-cotα
tan(π/2-α)=cotα
tan(π-α)=-tanα
tan(π+α)=tanα
诱导公式记背诀窍:奇变偶不变,符号看象限
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