问题 选择题
函数f(x)=excosx的图象在点(0,f(0))处的切线倾斜角的余弦值为(  )
A.-
5
5
B.
5
5
C.
2
2
D.1
答案

由题意得,f′(x)=excosx-exsinx,

∴在点(0,f(0))处的切线的斜率是:

f′(0)=e0cos0-e0sin0=1,

∴在点(0,f(0))处的切线倾斜角是:45°,

则倾斜角的余弦值是:

2
2

故选C.

单项选择题 A1/A2型题
问答题 简答题