Math II question? O.O

[MarieM]

<p>When the graph of y=Sin2x is drawn for all values of x between 10 degrees and 350 degrees, it crosses the x-axis
A) zero times
B) 1 time
C) 2 times
D) 3 times
E) 6 times</p>

<p>Barrons^ Model Test 2, Question 10.</p>

<p>The answer is E.</p>

<p>and I don't get it.</p>

<p>Sin2x=0 when 2x=0, 180, 360, 540, 720..
So..x can be 90, 180, 270, 360, 540, no?
Why not?
I mean..x should be between 10 and 350 degrees, not 2x, so why can't we include 360 and 540?</p>

<p>Can somebody please explain?</p>

[thebigone]

<p>no!
first you can just draw the function on your calculator for x between 10 and 350 degrees and count the points
or :
sin (2x)=0
then 2x= 0 , 180 , 360, 540 , 720…
so x = 0, 90, 180, 270, 360…
but x is between 10 and 350 degrees
so we have three solutions : 90, 180 and 270</p>

[MarieM]

<p>nevermind.
I’m dumb.
Seriously.
I surprise myself at times with it. xDD</p>

<p>Anyway, thanks thebigone</p>