The number of solutions of the equation x/100=sinx
A) 63
B)32
C) 33
D) 0
Since |sin x|<=1, then x<=100.
We partition the interval [0,100] into segments (0,2pi], (2pi,4pi], ..., (28pi,30pi], (30pi,100]. It is easy to see that there are two solutions in each interval except for (0,2pi] in which there is one solution, in total there are 31 positive solutions. So there must be 31 negative solutions. Since x=0 is also a solution, there are 31+31+1=63 solutions.