Chapter 6: Problem 8
Sketch each angle in standard position. (a) \(450^{\circ}\) (b) \(-180^{\circ}\) (c) \(270^{\circ}\)
Short Answer
Expert verified
Sketch 90°, 180°, and 270° angles starting from the positive x-axis.
Step by step solution
01
Determine the Reference Angle
For an angle, the reference angle can be found by finding the equivalent angle between 0° and 360°. If the given angle is greater than 360°, subtract 360° until it falls within the 0° to 360° range. If it is negative, keep adding 360° until it becomes positive.
02
Sketch the Angle 450°
For 450°, subtract 360° to find the equivalent angle: \[450° - 360° = 90°\] Sketch a 90° angle in standard position on the coordinate plane, starting from the positive x-axis to the positive y-axis.
03
Sketch the Angle -180°
For -180°, add 360° to find the equivalent angle: \[-180° + 360° = 180°\] Sketch a 180° angle in standard position, which is a straight line extending from the positive x-axis to the negative x-axis along the diameter of a circle.
04
Sketch the Angle 270°
For 270°, the angle directly falls between 0° and 360°, hence no need for conversion.
Sketch a 270° angle in standard position on the coordinate plane, starting from the positive x-axis to the negative y-axis.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Reference Angle
A reference angle is a crucial part of understanding angles on a coordinate plane. It helps simplify the process of sketching and working with angles. The reference angle is always found between the original angle and the nearest x-axis.
- To determine the reference angle, you must bring the given angle into the standard interval of 0° to 360°.
- For angles greater than 360°, subtract 360° repeatedly until it falls within 0° and 360°.
- If the angle is negative, add 360° repeatedly until the angle is positive.
Standard Position
In trigonometry, sketching angles is often done in what is called the 'standard position'. This method provides a consistent reference point for measuring angles. An angle is in standard position when:
- The vertex of the angle is at the origin of the coordinate plane.
- The initial side lies along the positive x-axis.
- The angle is measured from the initial side, moving counterclockwise for positive angles and clockwise for negative angles.
Coordinate Plane
The coordinate plane is a two-dimensional plane formed by the intersection of a vertical line (y-axis) and a horizontal line (x-axis). It is crucial when working with angles in trigonometry.
- It supports visualizing angles by providing a framework where angles start from the origin and open outwards.
- Aids in understanding how angles relate to each of the four quadrants, with each quadrant representing a specific range of degree measures.
- Helps in determining the signs of trigonometric functions based on the position of an angle's terminal side.
Positive and Negative Angles
Angles can be measured in either a positive or negative direction. This is a fundamental concept in trigonometry that affects how angles are sketched and understood.
- Positive angles are measured counterclockwise from the initial side on the positive x-axis.
- Negative angles are measured clockwise from the same initial side.
- Recognizing whether an angle is positive or negative is important when determining its direction and position on the coordinate plane.