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
8. Vectors
Direction of a Vector
4:00 minutes
Problem 10
Textbook Question
Textbook QuestionFind the magnitude and direction angle for each vector. Round angle measures to the nearest tenth, as necessary.
〈-4, -7〉
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Vector Magnitude
The magnitude of a vector is a measure of its length and is calculated using the Pythagorean theorem. For a vector represented as 〈x, y〉, the magnitude is given by the formula √(x² + y²). In this case, for the vector 〈-4, -7〉, the magnitude would be √((-4)² + (-7)²) = √(16 + 49) = √65.
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Direction Angle
The direction angle of a vector is the angle it makes with the positive x-axis, measured counterclockwise. It can be found using the arctangent function: θ = arctan(y/x). For the vector 〈-4, -7〉, the angle can be calculated as θ = arctan(-7/-4), which will yield an angle in the third quadrant since both components are negative.
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Quadrants in the Coordinate Plane
The coordinate plane is divided into four quadrants based on the signs of the x and y coordinates. The first quadrant has both coordinates positive, the second has a negative x and positive y, the third has both negative, and the fourth has a positive x and negative y. Understanding the quadrant is essential for determining the correct angle measure, as angles in different quadrants require adjustments to ensure they are expressed correctly.
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