Back to Extend trigonometric functions using unit circle — Problem 2 · Task Set 66

Exercises: Extend Trigonometric Functions Using the Unit Circle

Show all steps for each problem. Leave answers involving square roots in exact form (e.g., $\frac{\sqrt{2}}{2}$) unless otherwise stated.

Grade 9·21 problems·~30 min·Common Core Math - HS Functions·group·hsf-tf-a-2

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Fluency Practice

Evaluate each expression using the unit circle. Give exact values.

The angle $\frac{2\pi}{3}$ has its terminal side in Quadrant II. What are the signs of $\sin\!\left(\frac{2\pi}{3}\right)$ and $\cos\!\left(\frac{2\pi}{3}\right)$ ?

Both positive

$\sin > 0$ , $\cos < 0$

Both negative

$\sin < 0$ , $\cos > 0$