(Modeling) Speed of Light When a light ray travels from one medium, such as air, to another medium, such as water or glass, the speed of the light changes, and the light ray is bent, or refracted, at the boundary between the two media. (This is why objects under water appear to be in a different position from where they really are.) It can be shown in physics that these changes are related by Snell's law c₁ = sin θ₁ , c₂ sin θ₂ where c₁ is the speed of light in the first medium, c₂ is the speed of light in the second medium, and θ₁ and θ₂ are the angles shown in the figure. In Exercises 81 and 82, assume that c₁ = 3 x 10⁸ m per sec. Find the speed of light in the second medium for each of the following. a. θ₁ = 46°, θ₂ = 31° b. θ₁ = 39°, θ₂ = 28°
Table of contents
- 0. Review of College Algebra4h 43m
- 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
- OLD 1. Angles and the Trigonometric Functions Coming soon
- OLD 2. Trigonometric Functions graphs, Inverse Trigonometric Functions Coming soon
- OLD 3. Trigonometric Identities and Equations Coming soon
- OLD 4. Laws of Sines, Cosines and Vectors Coming soon
- OLD 5. Complex Numbers, Polar Coordinates and Parametric Equations Coming soon
- NEW (not used) 7. Laws of Sines, Cosines and Vectors Coming soon
- NEW (not used) 8. Vectors Coming soon
- NEW(not used) 9. Polar equations Coming soon
- NEW (not used) 11. Graphing Complex Numbers Coming soon
3. Unit Circle
Trigonometric Functions on the Unit Circle
Problem 45
Textbook Question
Find a calculator approximation to four decimal places for each circular function value.
sin 1.0472
Verified step by step guidance1
Recognize that the given angle 1.0472 is in radians, which is approximately equal to \( \frac{\pi}{3} \) radians (or 60 degrees).
Recall the definition of the sine function for an angle \( \theta \) in radians: \( \sin \theta \) gives the y-coordinate of the point on the unit circle corresponding to \( \theta \).
To find the sine of 1.0472 radians, you can use a scientific calculator set to radian mode.
Enter the value 1.0472 into the calculator and then press the sine function key to get the approximate value.
Round the result to four decimal places to obtain the final approximation for \( \sin 1.0472 \).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Radian Measure
Radian measure is a way to express angles based on the radius of a circle. One radian is the angle subtended by an arc equal in length to the radius. Understanding radians is essential because trigonometric functions like sine often use radian inputs rather than degrees.
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Converting between Degrees & Radians
Sine Function
The sine function relates an angle in a right triangle to the ratio of the length of the opposite side to the hypotenuse. On the unit circle, sine corresponds to the y-coordinate of a point at a given angle. Calculating sine for a radian value involves understanding this geometric interpretation.
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Graph of Sine and Cosine Function
Calculator Approximation and Rounding
Calculators provide decimal approximations of trigonometric values, which are often irrational numbers. Rounding to four decimal places means limiting the result to four digits after the decimal point, ensuring a balance between precision and simplicity in practical use.
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