Chapter 8: Problem 5
Without using your GDC, determine the exact values of all six trigonometric functions for the following angles. a) \(120^{\circ}\) b) \(135^{\circ}\) c) \(330^{\circ}\) d) \(270^{\circ}\) e) \(240^{\circ}\) f) \(\frac{5 \pi}{4}\) g) \(-\frac{\pi}{6}\) h) \(\frac{7 \pi}{6}\) i) \(-60^{\circ}\) j) \(-\frac{3 \pi}{2}\) k) \(\frac{5 \pi}{3}\) l)\(-210^{\circ}\) \(m)-\frac{\pi}{4}\) n) \(\pi\) o) \(4.25 \pi\)
Short Answer
Step by step solution
Understanding Reference Angles
Calculating Trigonometric Functions for a Specific Angle
Apply Sign Rules Based on Quadrant
Example Calculation for Each Angle
Repeat for Other Angles
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Exact Values
- \(30^{\circ}\), \(45^{\circ}\), and \(60^{\circ}\)
- their corresponding radian measures: \(\frac{\pi}{6}\), \(\frac{\pi}{4}\), and \(\frac{\pi}{3}\)
- \( \sin(30^{\circ}) = \frac{1}{2} \)
- \( \cos(45^{\circ}) = \frac{\sqrt{2}}{2} \)
- \( \tan(60^{\circ}) = \sqrt{3} \)
Reference Angles
- For angles in the first quadrant, the reference angle is the angle itself.
- In the second quadrant, it is found by subtracting the angle from \(180^{\circ}\) or \(\pi\) radians.
- In the third quadrant, subtract \(180^{\circ}\) or \(\pi\) from the angle.
- In the fourth quadrant, subtract the angle from \(360^{\circ}\) or \(2\pi\).
Sign Rules
- First Quadrant: All trigonometric functions (sine, cosine, tangent, cosecant, secant, and cotangent) have positive values.
- Second Quadrant: Only sine and cosecant remain positive, while cosine, secant, tangent, and cotangent are negative.
- Third Quadrant: Tangent and cotangent are positive, whereas sine, cosine, cosecant, and secant are negative.
- Fourth Quadrant: Cosine and secant are positive, with sine, cosecant, tangent, and cotangent negative.
Quadrant Analysis
- First Quadrant: This quadrant covers angles between \(0^{\circ}\) to \(90^{\circ}\) (or \(0\) to \(\frac{\pi}{2}\) radians). Here, all trigonometric functions are positive.
- Second Quadrant: Ranging from \(90^{\circ}\) to \(180^{\circ}\) (or \(\frac{\pi}{2}\) to \(\pi\)), only sine and cosecant are positive; others are negative.
- Third Quadrant: This covers \(180^{\circ}\) to \(270^{\circ}\) (or \(\pi\) to \(\frac{3\pi}{2}\)). Tangent and cotangent are positive here.
- Fourth Quadrant: From \(270^{\circ}\) to \(360^{\circ}\) (or \(\frac{3\pi}{2}\) to \(2\pi\)), cosine and secant are positive while the rest are negative.