How to scale graphs of sine and cosine functions?

I know how to find the amplitude and shifts.

I need help understanding how to scale the graphs and where the period actually is.

Please help, I'm confusing myself too much.

Question

How to scale graphs of sine and cosine functions?

I know how to find the amplitude and shifts.

I need help understanding how to scale the graphs and where the period actually is. 

Please help, I'm confusing myself too much.

anonymous · Answer

This is pre-calc

anonymous · Answer

http://www.purplemath.com/modules/triggrph.htm

anonymous · Answer

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"a" scales it