Math Problem Statement

How do you determine the quadrant for any given angle in standard position?

Solution

To determine the quadrant for any given angle in standard position, you can follow these steps:

1. Understand the Quadrants:

  • First Quadrant (0° to 90°): The angle is between 0° and 90°. Here, both sine and cosine are positive.
  • Second Quadrant (90° to 180°): The angle is between 90° and 180°. Here, sine is positive, but cosine is negative.
  • Third Quadrant (180° to 270°): The angle is between 180° and 270°. Here, both sine and cosine are negative.
  • Fourth Quadrant (270° to 360°): The angle is between 270° and 360°. Here, sine is negative, but cosine is positive.

2. Determine the Angle's Position:

  • If the angle is positive:

    • If it's between 0° and 90°, it's in the First Quadrant.
    • If it's between 90° and 180°, it's in the Second Quadrant.
    • If it's between 180° and 270°, it's in the Third Quadrant.
    • If it's between 270° and 360°, it's in the Fourth Quadrant.
  • If the angle is negative:

    • Add 360360^\circ to the negative angle until it becomes positive, and then apply the same quadrant rules as for a positive angle.
    • For example, if you have 75-75^\circ, you add 360360^\circ to get 285285^\circ, which is in the Fourth Quadrant.

3. Consider Coterminal Angles:

  • Coterminal Angles: These are angles that differ by multiples of 360360^\circ but have the same terminal side.
  • If the angle is greater than 360360^\circ or less than 00^\circ, subtract or add 360360^\circ until it falls within the 00^\circ to 360360^\circ range to determine the quadrant.

4. Example:

  • Angle 135135^\circ: Since 135135^\circ is between 90° and 180°, it lies in the Second Quadrant.
  • Angle 200-200^\circ: Add 360360^\circ to get 160160^\circ, which lies in the Second Quadrant.
  • Angle 400400^\circ: Subtract 360360^\circ to get 4040^\circ, which lies in the First Quadrant.

Would you like to explore any other concepts or have any specific questions?


Here are 5 related questions to consider:

  1. How can you find the reference angle for any given angle?
  2. What are the signs of trigonometric functions in each quadrant?
  3. How do you determine the exact value of trigonometric functions for common angles (e.g., 30°, 45°, 60°)?
  4. How do you convert between degrees and radians?
  5. What are the implications of an angle being in the third quadrant for sine and cosine values?

Tip: When working with angles, always remember that positive angles are measured counterclockwise, while negative angles are measured clockwise from the positive x-axis.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Angles
Quadrants

Formulas

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Theorems

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Suitable Grade Level

Grades 9-12