高二三角函数的计算
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高二三角函数的计算
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![高二三角函数的计算](/uploads/image/z/19889402-50-2.jpg?t=%E9%AB%98%E4%BA%8C%E4%B8%89%E8%A7%92%E5%87%BD%E6%95%B0%E7%9A%84%E8%AE%A1%E7%AE%97)
9.sin(180+α)+cos(90+α)=-a.
-sinα-sinα=-a.
2sinα=a,
sinα=a/2.
cos(270°-α)+2sin(360°-α)=-sinα-2sinα=-3sinα=-3*(α/2)=-3a/2.
∴原式=-3a/2.
11.原式=(√3/2)^2+(-1)+1-3/4+1/2.
=1/2.
12.原式=√[(1-2sin(3*360°+5°)*(-sin(6*360°-85°)/(cos5°+cos95°].
=√[(1-2sin5°*cos5°)/( cos5°-sin5°)].
=√[(cos5-sin5)^2/(cos5-sin5)].∵cos5°>sin5°
∴原式√(cos5°-sin5°).
-sinα-sinα=-a.
2sinα=a,
sinα=a/2.
cos(270°-α)+2sin(360°-α)=-sinα-2sinα=-3sinα=-3*(α/2)=-3a/2.
∴原式=-3a/2.
11.原式=(√3/2)^2+(-1)+1-3/4+1/2.
=1/2.
12.原式=√[(1-2sin(3*360°+5°)*(-sin(6*360°-85°)/(cos5°+cos95°].
=√[(1-2sin5°*cos5°)/( cos5°-sin5°)].
=√[(cos5-sin5)^2/(cos5-sin5)].∵cos5°>sin5°
∴原式√(cos5°-sin5°).