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# Interpreting trigonometric graphs in context

When a trigonometric function models a real-world relationship, we can assign meaning to its midline, amplitude and period. Created by Sal Khan.

## Want to join the conversation?

• I thought the practice from the last chapter said that midline is 1/4 of a period, so 4 x 15 right? AHhhhh i keep confusing myself
• No, 4x10, because the midline is x=15 and max is x=25, min is x = 5. 25-15 = 10, and 15-5=10 as well.

Generally its 4 x difference between x of midline and x of the immediate next min or max.
• I didn't understand why the mid-line represents the center of rotation?
• The midline represents the average of the max_Yvalue, min_Yvalue
• Oh mah lawd
• I never knew that Ferris wheels went that fast...
• I'm confused, if in the sin(x) function the independent variable corresponds to an angle in radians, why is the independent variable a duration in this video?
• It is modeled in the word problem. The independent variable isn't always going to be radians. It could represent something else.
• Is the period always the same?
• Not necessarily. Functions can have different periods