Table of contents
- 0. Review of College Algebra4h 43m
- 1. Measuring Angles39m
- 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
- 7. Non-Right Triangles1h 38m
- 8. Vectors2h 25m
- 9. Polar Equations2h 5m
- 10. Parametric Equations1h 6m
- 11. Graphing Complex Numbers1h 7m
2. Trigonometric Functions on Right Triangles
Trigonometric Functions on Right Triangles
Problem 33b
Textbook Question
In Exercises 23–34, find the exact value of each of the remaining trigonometric functions of θ. sec θ = -3, tan θ > 0
![](/channels/images/assetPage/verifiedSolution.png)
1
<insert step 1: Understand the given information. We know that \( \sec \theta = -3 \) and \( \tan \theta > 0 \). The secant function is the reciprocal of the cosine function, so \( \cos \theta = -\frac{1}{3} \).>
<insert step 2: Determine the quadrant where \( \theta \) is located. Since \( \sec \theta = -3 \) (meaning \( \cos \theta < 0 \)) and \( \tan \theta > 0 \), \( \theta \) must be in the third quadrant, where both sine and cosine are negative, but tangent is positive.>
<insert step 3: Use the Pythagorean identity to find \( \sin \theta \). The identity is \( \sin^2 \theta + \cos^2 \theta = 1 \). Substitute \( \cos \theta = -\frac{1}{3} \) into the equation: \( \sin^2 \theta + \left(-\frac{1}{3}\right)^2 = 1 \).>
<insert step 4: Solve for \( \sin \theta \). Simplify the equation from step 3 to find \( \sin^2 \theta \), and then take the square root to find \( \sin \theta \). Remember that in the third quadrant, \( \sin \theta \) is negative.>
<insert step 5: Calculate the remaining trigonometric functions. Use \( \sin \theta \) and \( \cos \theta \) to find \( \tan \theta = \frac{\sin \theta}{\cos \theta} \), \( \csc \theta = \frac{1}{\sin \theta} \), and \( \cot \theta = \frac{1}{\tan \theta} \).>
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Trigonometric Functions
Trigonometric functions relate the angles of a triangle to the lengths of its sides. The primary functions include sine, cosine, tangent, secant, cosecant, and cotangent. Understanding these functions is essential for solving problems involving angles and their relationships, particularly in right triangles.
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Secant and Tangent Relationships
Secant (sec) is the reciprocal of cosine, defined as sec θ = 1/cos θ. The tangent (tan) function is the ratio of sine to cosine, tan θ = sin θ/cos θ. Given sec θ = -3, we can derive the cosine value and subsequently find the sine value, which helps in determining other trigonometric functions.
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Graphs of Secant and Cosecant Functions
Quadrants and Signs of Trigonometric Functions
The signs of trigonometric functions depend on the quadrant in which the angle θ lies. In this case, since sec θ is negative and tan θ is positive, θ must be in the third quadrant, where sine is negative and cosine is negative, while tangent is positive. This understanding is crucial for determining the exact values of the remaining trigonometric functions.
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