Exercises: Pythagorean Identity: Proof and Applications

Grade 9·21 problems·~35 min·Common Core Math - HS Functions·group·hsf-tf-c-8

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Recall / Warm-Up

On the unit circle, a point at angle $\theta$ has coordinates $(x, y)$ .
Which of the following correctly identifies $\sin\theta$ and $\cos\theta$ ?

$\sin\theta = x$ and $\cos\theta = y$

$\sin\theta = y$ and $\cos\theta = x$

$\sin\theta = \frac{y}{x}$ and $\cos\theta = \frac{x}{y}$

$\sin\theta = \frac{x}{y}$ and $\cos\theta = \frac{y}{x}$