I'm assuming you mean and not .

If you know the graph of the basic sine function, you would know that the x-intercepts are , for any integer n (in other words, multiples of pi). Putting a number greater than 1 in front of x transforms the graph -- you have a horizontal shrink by a factor of that number. So in our case, is a horizontal shrink of by a factor of 2.

This effectively means that the x-intercepts occur twice as often, ie. , for any integer n.

Another example: say it's . Then its x-intercepts would be , for any integer n.

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