![已知tanα=2,sinα+cosα＜0,求[sin(2π-α)*sin(π+α)*cos(-π+α)][sin(3π-α)*cos(π+α)]的值,第1張](data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw== "已知tanα=2,sinα+cosα＜0,求[sin(2π-α)*sin(π+α)*cos(-π+α)][sin(3π-α)*cos(π+α)]的值,第1張")
已知tanα=2,sinα cosα＜0,求[sin(2π-α)*sin(π α)*cos(-π α)]/[sin(3π-α)*cos(π α)]的值網友廻答：
- 解析：∵tana=sina/cosa=2＞0,∴sina=2cosa,sina和cosa同號,又sinα cosα＜0,∴sina＜0,cosa＜0,由(sina)^2 (cosa)^2=1,可得sina=-2√5/5,cosa=-√5/5,原式=【sin(-a)*(-sina)*(-cosa)]/[sina*(-cosa)]=sina=-2√5/...
admin![已知tanα=2,sinα+cosα＜0,求[sin(2π-α)*sin(π+α)*cos(-π+α)][sin(3π-α)*cos(π+α)]的值,第1張](/pic/已知tanα=2,sinα+cosα＜0,求[sin(2π-α)*sin(π+α)*cos(-π+α)][sin(3π-α)*cos(π+α)]的值.jpg "已知tanα=2,sinα+cosα＜0,求[sin(2π-α)*sin(π+α)*cos(-π+α)][sin(3π-α)*cos(π+α)]的值,第1張")
![已知tanα=2,sinα+cosα＜0,求[sin(2π-α)*sin(π+α)*cos(-π+α)][sin(3π-α)*cos(π+α)]的值,第2張](/statics/default/images/niming.jpg "已知tanα=2,sinα+cosα＜0,求[sin(2π-α)*sin(π+α)*cos(-π+α)][sin(3π-α)*cos(π+α)]的值,第2張")
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