求三角函数值5
求值:tan20°+4cos70°
解: `tan20°+4cos70° =sin20°/cos20°+4sin20° =(sin20°+4sin20°cos20°)/cos20° =(sin20°+sin40°+sin40°)/cos20° =(2sin30°cos10°+sin40°)/cos20° =(sin80°+sin40°)/cos20° =2sin60°cos20°/cos20° =√3
答:为方便把"度"这个字省略.呵呵. tan20+4cos70=sin20/cos20+4sin20=(sin20+4sin20*cos20)/cos20 =(si...详情>>
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