練習題庫/gsat・難度 3當 f(x)=3sinx−4cosxf(x)=3\sin x-4\cos xf(x)=3sinx−4cosx 取得最大值時，(sinx,cosx)(\sin x,\cos x)(sinx,cosx) 為下列何者？(A)(−35,45)\left(-\frac{3}{5},\frac{4}{5}\right)(−53,54)(B)(−45,35)\left(-\frac{4}{5},\frac{3}{5}\right)(−54,53)(C)(35,−45)\left(\frac{3}{5},-\frac{4}{5}\right)(53,−54)(D)(35,45)\left(\frac{3}{5},\frac{4}{5}\right)(53,54)(E)(45,−35)\left(\frac{4}{5},-\frac{3}{5}\right)(54,−53)登入後即可作答並查看完整詳解（每日免費 5 題）。