In Exercises 49–59, find the exact value of each expression. Do not use a calculator. sin(-𝜋/3)
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- 0. Review of College Algebra4h 45m
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- 2. Trigonometric Functions on Right Triangles2h 5m
- 3. Unit Circle1h 19m
- 4. Graphing Trigonometric Functions1h 19m
- 5. Inverse Trigonometric Functions and Basic Trigonometric Equations1h 41m
- 6. Trigonometric Identities and More Equations2h 34m
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3. Unit Circle
Reference Angles
Problem 9
Textbook Question
In Exercises 8–13, find the exact value of each expression. Do not use a calculator. tan 300°
Verified step by step guidance1
Recall that the tangent function has a period of 180°, so \( \tan(300^\circ) = \tan(300^\circ - 180^\circ) = \tan(120^\circ) \).
Identify the reference angle for 120°. Since 120° is in the second quadrant, the reference angle is \( 180^\circ - 120^\circ = 60^\circ \).
Determine the sign of tangent in the second quadrant. Tangent is negative in the second quadrant because sine is positive and cosine is negative, and \( \tan \theta = \frac{\sin \theta}{\cos \theta} \).
Use the exact value of \( \tan 60^\circ \), which is \( \sqrt{3} \).
Combine the sign and the reference angle value to write \( \tan 300^\circ = -\sqrt{3} \).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Reference Angles and Quadrants
Understanding reference angles helps simplify trigonometric values by relating them to acute angles. The angle 300° lies in the fourth quadrant, where tangent values are negative. Identifying the quadrant determines the sign of the trigonometric function.
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Tangent Function Definition
The tangent of an angle in standard position is the ratio of the sine to the cosine of that angle (tan θ = sin θ / cos θ). Knowing this relationship allows calculation of tangent values using known sine and cosine values of reference angles.
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Introduction to Tangent Graph
Exact Values of Special Angles
Certain angles like 30°, 45°, and 60° have well-known exact sine, cosine, and tangent values. Since 300° corresponds to 360° - 60°, using the exact values for 60° helps find the exact tangent of 300° without a calculator.
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