则直线ax-by c的倾斜角为多少?
函数y=asinx-bcosx的一条对称轴是x=四分之派,则直线ax-by c的倾斜角为多少?高一数学题
y=f(x)=asinx-bcosx一条对称轴是x=π/4,则: f[(π/4)+x]=f[(π/4)-x],既: asin[(π/4)+x]-bcos[(π/4)+x]=asin[(π/4)-x]-bcos[(π/4)-x] 2acos(π/4)sinx+2bsin(π/4)sinx=0 (a+b)sinx=0 a=-b 则直线ax-by+c=0的斜率=a/b=-1,倾斜角为3π/4
答:详情>>