Think About It  The figure shows point P(x, y) on a unit circle and right triangle OAP.(a)...

Think About It  The figure shows point P(x, y) on a unit circle and right triangle OAP.

(a) Find sin t and cos t using the unit circle definitions of sine and cosine (from Section 1.2).

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(b) What is the value of r? Explain.

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(c) Use the definitions of sine and cosine given in this section to find sin θ and cos θ. Write your answers in terms of x and y.

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(d) Based on your answers to parts (a) and (c), what can you conclude?