已知f=[sin(π-α)cos(2π-α)tan(-π-α)]/sin(-π-α),⑴化简f(a)、⑵若α是第三象限,且cos﹙α-3π/2且cos﹙α-3π/2﹚=1/5,求f(a)的值、⑶若α=﹣1860°,求f(a)的值⑴-sinα ⑵ 1/5 ⑶根号3/2我要具体步骤.
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![已知f=[sin(π-α)cos(2π-α)tan(-π-α)]/sin(-π-α),⑴化简f(a)、⑵若α是第三象限,且cos﹙α-3π/2且cos﹙α-3π/2﹚=1/5,求f(a)的值、⑶若α=﹣1860°,求f(a)的值⑴-sinα ⑵ 1/5 ⑶根号3/2我要具体步骤.](/uploads/image/z/2496550-22-0.jpg?t=%E5%B7%B2%E7%9F%A5f%3D%5Bsin%28%CF%80-%CE%B1%29cos%282%CF%80-%CE%B1%29tan%28-%CF%80-%CE%B1%29%5D%2Fsin%28-%CF%80-%CE%B1%29%2C%E2%91%B4%E5%8C%96%E7%AE%80f%28a%29%E3%80%81%E2%91%B5%E8%8B%A5%CE%B1%E6%98%AF%E7%AC%AC%E4%B8%89%E8%B1%A1%E9%99%90%2C%E4%B8%94cos%EF%B9%99%CE%B1%EF%BC%8D3%CF%80%2F2%E4%B8%94cos%EF%B9%99%CE%B1%EF%BC%8D3%CF%80%2F2%EF%B9%9A%3D1%2F5%2C%E6%B1%82f%EF%BC%88a%EF%BC%89%E7%9A%84%E5%80%BC%E3%80%81%E2%91%B6%E8%8B%A5%CE%B1%EF%BC%9D%EF%B9%A31860%C2%B0%2C%E6%B1%82f%28a%29%E7%9A%84%E5%80%BC%E2%91%B4-sin%CE%B1+%E2%91%B5+1%2F5+%E2%91%B6%E6%A0%B9%E5%8F%B73%2F2%E6%88%91%E8%A6%81%E5%85%B7%E4%BD%93%E6%AD%A5%E9%AA%A4.)
已知f=[sin(π-α)cos(2π-α)tan(-π-α)]/sin(-π-α),⑴化简f(a)、⑵若α是第三象限,且cos﹙α-3π/2且cos﹙α-3π/2﹚=1/5,求f(a)的值、⑶若α=﹣1860°,求f(a)的值⑴-sinα ⑵ 1/5 ⑶根号3/2我要具体步骤.
已知f=[sin(π-α)cos(2π-α)tan(-π-α)]/sin(-π-α),⑴化简f(a)、⑵若α是第三象限,且cos﹙α-3π/2
且cos﹙α-3π/2﹚=1/5,求f(a)的值、⑶若α=﹣1860°,求f(a)的值
⑴-sinα ⑵ 1/5 ⑶根号3/2
我要具体步骤.
已知f=[sin(π-α)cos(2π-α)tan(-π-α)]/sin(-π-α),⑴化简f(a)、⑵若α是第三象限,且cos﹙α-3π/2且cos﹙α-3π/2﹚=1/5,求f(a)的值、⑶若α=﹣1860°,求f(a)的值⑴-sinα ⑵ 1/5 ⑶根号3/2我要具体步骤.
⑴
f(α) = [sin(π-α)cos(2π-α)tan(-π-α)]/sin(-π-α)
= [sin(α)cos(-α)tan(-α)]/sin(α)
= cos(-α)tan(-α)
= cos(-α) * sin(-α) / cos(-α)
= sin(-α)
= -sin(α)
⑵
cos﹙α - 3π/2﹚=cos﹙-2π + π/2 + α ﹚= cos(π/2 + α) = -sin(α) =1/5
∴ f(α) = -sin(α) = 1/5
⑶
f(α) = -sin(α) = -sin(-1860°) = -sin(-5×360°- 60°) = -sin(-60°) = sin60°= √3/2
⑴
f(α) = [sin(π-α)*cos(2π-α)*tan(-π-α)]/sin(-π-α)
= [sin(α)*cos(-α)*tan(-α)]/sin(α)
= cos(-α)*tan(-α)
= cos(-α) * tan(-α)
= sin(-α)
= -s...
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⑴
f(α) = [sin(π-α)*cos(2π-α)*tan(-π-α)]/sin(-π-α)
= [sin(α)*cos(-α)*tan(-α)]/sin(α)
= cos(-α)*tan(-α)
= cos(-α) * tan(-α)
= sin(-α)
= -sin(α)
⑵
cos﹙α - 3π/2﹚=cos﹙-2π + π/2 + α ﹚= cos(π/2 + α) = -sin(α) =1/5
∴ f(α) = -sin(α) = 1/5
⑶
f(α) = -sin(α) = -sin(-1860°) = -sin(-5×360°- 60°) = -sin(-60°) = sin60°= √3/2
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