Use Identities to Find the Indicated Value for Each Angle $\cos 2 \theta = \frac { 4 } { 5 }$

question 102

Multiple Choice

Use identities to find the indicated value for each angle measure.
- $\cos 2 \theta = \frac { 4 } { 5 }$ and $\theta$ terminates in quadrant III $\quad$ Find $\cos \theta$ .

• A) \(\cos \theta = \frac { 3 \sqrt { 10 } } { 10 }\)
• B) \(\cos \theta = 0\)
• C) \(\cos \theta = - \frac { \sqrt { 10 } } { 3 }\)
• D) \(\cos \theta = - \frac { 3 \sqrt { } } { 10 }\)

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Definitions:

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