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Lesson 2

1. Lesson 2

1.6. Explore 2

Mathematics 30-1 Module 4

Module 4: Foundations of Trigonometry

 

All of the angles you used in Try This 1 and Try This 2 had terminal arms in the same position. Angles with the same terminal arm are called coterminal angles. The following angles are coterminal angles.

 

This is a sketch of a 360-degree angle drawn in standard position. This is a sketch of a 720-degree angle drawn in standard position. This is a sketch of a 1080-degree angle drawn in standard position.


textbook

Read “Coterminal Angles” and “Example 2” on pages 170 and 171 of the textbook. By the end of this reading you should understand the definition of coterminal angles, and you should know how coterminal angles are determined. As you read, think about the following questions:

  • How are coterminal angles drawn?
  • How are positive and negative coterminal angles determined?
  • What are the differences between finding coterminal angles in degrees and finding coterminal angles in radians?
Self-Check 1

 

For each angle in standard position, determine one positive and one negative angle measure that is coterminal with the angle in standard position.1

  1. 270° Answer
  2.  Answer

1 Source: Pre-Calculus 12. Whitby, ON: McGraw-Hill Ryerson, 2011. Reproduced with permission.