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Unformatted text preview: Section 4.3 – Unit Circle Trigonometry 1 Section 4.3 Trigonometric Functions of Angles An angle is formed by two rays that have a common endpoint (vertex). One ray is called the initial side and the other the terminal side . A terminal angle can lie in any quadrant, on the xaxis or yaxis. An angle is in standard position if the vertex is at the origin of the twodimensional plane and its initial side lies along the positive xaxis. Positive angles are generated by counterclockwise rotation. Negative angles are generated by clockwise rotation. Section 4.3 – Unit Circle Trigonometry 2 The Reference Angle or Reference Number Let θ be an angle in standard position. The reference angle associated with θ is the acute angle (with positive measure) formed by the xaxis and the terminal side of the angle θ . When radian measure is used, the reference angle is sometimes referred to as the reference number (because a radian angle measure is a real number). Example 1: Draw each angle in standard position and specify the reference angle. a. 405 o Note: Notice that in part a. 405 terminates in the same position as 45 . These type of angles are called coterminal angles . Every angle has infinitely many coterminal angles. Every angle has infinitely many coterminal angles....
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This note was uploaded on 02/20/2012 for the course MATH 1330 taught by Professor Staff during the Fall '08 term at University of Houston.
 Fall '08
 Staff
 Angles

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