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Finding the Value of Trig Functions Using Reflections

We can use reflections to help us evaluate trig functions.

Example: Evaluate equation image indicator

refl on unit circle 2.png

Solution

We know that sine corresponds to the y-value of the point on the unit circle.

So if we know that the coordinate associated with π/6 radians is equation image indicator , then .

We can simply reflect equation image indicator across the x-axis to find .