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