1 / 21

Chapter 13 Sec 2

Chapter 13 Sec 2. Angles and Degree Measure. Standard Position. An angle in standard position has its vertex at the origin and initial side on the positive x– axis . terminal side. initial side. Positively Counterclockwise.

soo
Télécharger la présentation

Chapter 13 Sec 2

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 13 Sec 2 Angles and Degree Measure

  2. Standard Position • An angle in standard positionhas its vertex at the origin and initial side on the positive x–axis. terminal side initial side

  3. Positively Counterclockwise • Angles that have a counterclockwise rotation have a positive measure. 90º 130 180º 0º 270º

  4. Clockwise means negative • Angles that have a clockwise rotation have a negative measure. – 270º – 180º 0º – 130 – 90º

  5. Unit Circle Now let’s look at angle measures 30, 150, 210, and 330. They all form a 30° angle with the x-axis, so they should all have the same sine, cosine, and tangent values…only the signs will change! The angle to the nearest x-axis is called the reference angle. All angles with the same reference angle will have the same trig values except for sign changes. 150° 30° 180° 30º 30º (1, 0) 30º (–1, 0) 30º 210° 330°

  6. Unit Circle A unit circle is a circle with radius 1. If we have an angle between 0o and 90oin standard position. Let P(x, y) be the point of intersection. If a perpendicular segment is drawn we create a right triangle, where y is opposite θ and x is adjacent to θ. Right triangles can be formed for angles greater than 90o, simply use the reference angle.

  7. Radian…still s P(x, y) α A point P(x, y) is on the unit circle if and only ifits distance from the origin is 1. The radian measure of an angle is the length of the corresponding arc on the unit circle. Since

  8. Degree/Radian Conversion

  9. Example 1 a. Change 115o to radian measure in terms of π.. b. Change radian to degree measure.

  10. 30° and 45° Radians You will need to know these conversions.

  11. Coterminal Angles • Coterminal angles are angles that have the same initial and terminal side, but differ by the number of rotations. • Since one rotation equals 360, the measures of coterminal angles differ by multiples of 360. 60 300 60 + 360 = 300 – 360 = 420 – 60

  12. Example 2 Find one positive and one negative coterminal angle. a. 45o 45o + 360o = 405o and 45o– 360o = –315o b. 225o 225o+ 360o= 585oand 225o– 360o = –135o

  13. Chapter 13 Sec 3 Trigonometric Functions

  14. Radius other than 1. • Suppose we have a hypotenuse with a length other than 1. For our example we’ll use r as the length. • In standard position r extends from the Origin to point P(x, y).

  15. Quadrantal Angle • If a terminal side of an angle coincides with one of the axes, the angle is called a quadrantal angle. See below for examples: • A full rotation around the circle is 360o. Measures more than 360o represent multiple rotations.

  16. Reference Angles To find the values of trig functions of angles greater than 90, you will need to know how to find the measures of the reference angle. If θ in nonquadrantal, its reference angleis formed by the terminal side of the given angle and the x-axis.

  17. Example 1 Find the reference angle for each angle. a. 312o Since 312o is between 270o and 360o the terminal side is in fourth quad. Therefore, 360o – 312o = 48o. b. –195o the coterminal angle is 360o – 195o = 165o this put us in the second quadrant so… 180o – 165o = 15o

  18. Determining Sign 90° (0, 1) All All values are positive Students Sine values are positive (csc, too) 180° 0°/360° (–1, 0) (1, 0) Calculus Cosine values are positive (sec, too) Take Tangent values are positive (cot, too) 270° (0, –1)

  19. Example 2 Find the values of the six trigonometric functions for angle θ in standard position if a point with coordinates (–15, 20) lies on the terminal side.

  20. Example 3 Find the values of the six trigonometric functions Suppose θis an angle in standard position whose terminal side lies in the Quadrant III. If find the remaining five trigonometric functions of θ.

  21. Daily Assignment • Chapter 13 Sections 2 & 3 • Study Guide • Pg 177 • #4 – 7 • Pg 178 – 180 Odd

More Related