13-10-09 Number of points of intersection.

What is the number of points of intersection of sin x and sin (sin x) in the interval [0, 2 pi]

13 Answers

11
Devil ·

Is it 3?

21
eragon24 _Retired ·

ya its 3 only....

red is sin(sinx)
black is sinx

1
Arshad ~Died~ ·

yes i also think 3...

24
eureka123 ·

sin(sinx)=sinx
=>sinx=nπ+(-1)nx

n=0 => sinx=x =>One soln( x=0)
n=1 => sinx=Ï€-x =>One soln(x=Ï€)
n=2 => sinx=2Ï€+x =>no soln

*Edit*
n=-2 =>sinx=-2Ï€+x =>x=2Ï€ is a soln
So 3 soln in x ε [0,2π]
*Edit*

1
Arshad ~Died~ ·

nishant sir wont give such an easy question...i think there is something else to it also....
@eure 2pi is also a solution

21
eragon24 _Retired ·

@eure yaar 3 soln toh already evident . i.e at x=0,pie,2pie.......i thnk there is no other soln other then these.........

24
eureka123 ·

yaah ..that i know....but why not coming htrough my approach

spot the mistake

1
Arshad ~Died~ ·

sina=sinb implies a=npi+(-1)^n b only when a belongs to [-pi/2,pi/2]

[299]
i found a cool smiley..yippeeee

1
Unicorn--- Extinct!! ·

Yeah...3 solutions only.

1357
Manish Shankar ·

eureka try n=-2

24
eureka123 ·

yeah n=-2 works...

62
Lokesh Verma ·

"nishant sir wont give such an easy question...i think there is something else to it also...."

LOl.. :D

No guys I give easy questions most of the time I think [3]

All I wanted to see is a graphical approach and deepak and the rest of you have done it perfectly :)

1
Arshad ~Died~ ·

arey sir i thought that as u gave it.....there may be some unexpected twist in it....
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