精品偷拍一区二区三区,亚洲精品永久 码,亚洲综合日韩精品欧美国产,亚洲国产日韩a在线亚洲

  • <center id="usuqs"></center>
  • 
    
  • 已知sinα是方程5x^2-7x-6=0的根α是第三象限,則{[sin(α-3/2π)cos(3/2π-α)]/[cos(π/2-α)sin(π/2+α)]}×tan^2(π-α)=

    已知sinα是方程5x^2-7x-6=0的根α是第三象限,則{[sin(α-3/2π)cos(3/2π-α)]/[cos(π/2-α)sin(π/2+α)]}×tan^2(π-α)=
    {[sin(α-3/2π)cos(3/2π-α)]為分子,cos(π/2-α)sin(π/2+α)]為分母,與tan^2(π-α)相乘
    數(shù)學(xué)人氣:157 ℃時(shí)間:2019-10-11 14:38:11
    優(yōu)質(zhì)解答
    {[sin(α-3/2π)cos(3/2π-α)]/[cos(π/2-α)sin(π/2+α)]}×tan^2(π-α)
    ={-sin(3/2π-a)cos(3/2π-α)]/[cos(π/2-α)sin(π/2+α)]}×tan^2(π-α)
    ={-1/2sin(3π-2a)]/[cos(π/2-α)sin(π/2+α)]}×tan²α
    ={-1/2sin2a]/[sinacosa]}tan²α
    ={-sin2a]/[2sinacosa]}tan²α
    =-tan²α
    5x^2-7x-6=0
    1 -2
    5 3
    (x-2)(5x+3)=0
    sina=-3/5
    cosa=-4/5
    tana=3/4
    tan²a=9/16
    ∴-9/16
    我來回答
    類似推薦
    請使用1024x768 IE6.0或更高版本瀏覽器瀏覽本站點(diǎn),以保證最佳閱讀效果。本頁提供作業(yè)小助手,一起搜作業(yè)以及作業(yè)好幫手最新版!
    版權(quán)所有 CopyRight © 2012-2024 作業(yè)小助手 All Rights Reserved. 手機(jī)版