In Exercises 63–82, use a sketch to find the exact value of each expression. _ sin (cos⁻¹ √2/2)
Table of contents
- 0. Review of College Algebra4h 45m
- 1. Measuring Angles40m
- 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
5. Inverse Trigonometric Functions and Basic Trigonometric Equations
Inverse Sine, Cosine, & Tangent
Problem 91
Textbook Question
In Exercises 83–94, use a right triangle to write each expression as an algebraic expression. Assume that x is positive and that the given inverse trigonometric function is defined for the expression in x. ___ sec (sin⁻¹ x/√x²+4)
Verified step by step guidance1
Identify the angle \( \theta \) such that \( \theta = \sin^{-1} \left( \frac{x}{\sqrt{x^2 + 4}} \right) \). This means \( \sin \theta = \frac{x}{\sqrt{x^2 + 4}} \).
Draw a right triangle where the angle \( \theta \) has an opposite side of length \( x \) and a hypotenuse of length \( \sqrt{x^2 + 4} \) based on the sine definition \( \sin \theta = \frac{\text{opposite}}{\text{hypotenuse}} \).
Use the Pythagorean theorem to find the adjacent side of the triangle: \( \text{adjacent} = \sqrt{(\text{hypotenuse})^2 - (\text{opposite})^2} = \sqrt{(\sqrt{x^2 + 4})^2 - x^2} \).
Simplify the adjacent side expression: \( \sqrt{x^2 + 4 - x^2} = \sqrt{4} = 2 \).
Recall that \( \sec \theta = \frac{\text{hypotenuse}}{\text{adjacent}} \). Substitute the known values to write \( \sec (\sin^{-1} (\frac{x}{\sqrt{x^2 + 4}})) = \frac{\sqrt{x^2 + 4}}{2} \) as the algebraic expression.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Inverse Trigonometric Functions
Inverse trigonometric functions, like sin⁻¹ (arcsin), return the angle whose trigonometric ratio equals a given value. Understanding their domain and range is essential, as they help translate between angle measures and ratio values, especially when constructing right triangles.
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Introduction to Inverse Trig Functions
Right Triangle Trigonometry
Right triangle trigonometry relates the sides and angles of a right triangle using ratios such as sine, cosine, and secant. By interpreting inverse trig expressions as angles in a triangle, one can find unknown sides or other trigonometric values algebraically.
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45-45-90 Triangles
Algebraic Manipulation of Trigonometric Expressions
Converting trigonometric expressions involving inverse functions into algebraic forms requires substituting sides of a triangle and simplifying. This often involves using the Pythagorean theorem and expressing trigonometric ratios in terms of the variable x.
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Simplifying Trig Expressions
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