Find all values of θ, if θ is in the interval [0°, 360°) and has the given function value. cos θ = -½
Ch. 2 - Acute Angles and Right Triangles
Chapter 3, Problem 19
Find exact values of the six trigonometric functions of each angle. Rationalize denominators when applicable. See Examples 2, 3, and 5. 300°
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Recognize that the angle 300° is in the fourth quadrant of the unit circle, where cosine is positive and sine is negative.
Find the reference angle by subtracting 300° from 360°, which gives \$360° - 300° = 60°$.
Recall the exact values of sine and cosine for the reference angle 60°: \(\sin 60° = \frac{\sqrt{3}}{2}\) and \(\cos 60° = \frac{1}{2}\).
Determine the sine and cosine of 300° using the signs in the fourth quadrant: \(\sin 300° = -\sin 60° = -\frac{\sqrt{3}}{2}\) and \(\cos 300° = \cos 60° = \frac{1}{2}\).
Calculate the remaining four trigonometric functions using the definitions: \(\tan 300° = \frac{\sin 300°}{\cos 300°}\), \(\csc 300° = \frac{1}{\sin 300°}\), \(\sec 300° = \frac{1}{\cos 300°}\), and \(\cot 300° = \frac{1}{\tan 300°}\). Remember to rationalize denominators where necessary.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Unit Circle and Angle Measurement
The unit circle is a circle with radius 1 centered at the origin, used to define trigonometric functions for all angles. Angles like 300° correspond to specific points on the unit circle, where coordinates (x, y) represent cosine and sine values respectively. Understanding how to locate angles on the unit circle is essential for finding exact trigonometric values.
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Introduction to the Unit Circle
Definition of the Six Trigonometric Functions
The six trigonometric functions are sine, cosine, tangent, cosecant, secant, and cotangent. Sine and cosine are based on the y and x coordinates of the unit circle point, while tangent is sine divided by cosine. The reciprocal functions (cosecant, secant, cotangent) are the inverses of sine, cosine, and tangent respectively, and knowing these definitions helps compute all values.
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Introduction to Trigonometric Functions
Rationalizing Denominators
Rationalizing denominators involves eliminating radicals from the denominator of a fraction by multiplying numerator and denominator by a suitable expression. This process is important for expressing exact trigonometric values in a simplified and standardized form, especially when the denominator contains square roots, ensuring clarity and consistency in answers.
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Rationalizing Denominators
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