1. If the period of the function f(x) = 4cos(x/2k) is 360度, k=?
A. 1/4
B. 1/2
C. 1
D. 2
2. At how many points does the graph of y=sin(x/2) cut the x-axis for 0度<=x<=720度.
A.0
B.1
C.2
D.3
3. At how many points does the graph of y=2sin2x cut the x-axis for 0度<=x<=360度?
A.4
B.5
C.6
D.7
maths f.5
2011-07-21 6:19 pm
回答 (2)
2011-07-21 9:01 pm
✔ 最佳答案
1.the period of the function g(x)=cos(x) is 360度
the period of the function f(x) = 4cos(x/2k) is 2k*360度 2k*360度=360度
2k=1
k=1/2Ans: B. 1/22.
0度<=x<=720度
0度<=x/2<=360度 sin(x/2)=0
x/2=0度 or x/2=180度 or x/2=360度
x=0度 or x=360度 or x=720度Ans: D. 33.
0度<=x<=360度
0度<=2x<=720度 2sin(2x)=0
sin(2x)=0
2x=0度 or 2x=180度 or 2x=360度 or 2x=540度 or 2x=720度
x=0度 or x=90度 or x=180度 or x=270度 or x=360度Ans: B. 5
2011-07-21 9:00 pm
1. period = 360 degree, so 1/2k = 1, k = 1/2. B
2. 3 points. x = 0, 360 and 720. D
3. 5 points. x = 0, 90, 180, 270, 360. B
2. 3 points. x = 0, 360 and 720. D
3. 5 points. x = 0, 90, 180, 270, 360. B
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