150 likes | 526 Views
6.3 Angles & Radian Measure. Objectives: Use a rotating Ray to extend the definition of angle measure to negative angles and angles greater than 180°. Define Radian Measure and convert angle measures between degrees and radians. Angles of Rotation.
E N D
6.3 Angles & Radian Measure Objectives: Use a rotating Ray to extend the definition of angle measure to negative angles and angles greater than 180°. Define Radian Measure and convert angle measures between degrees and radians.
Angles of Rotation Positive angles are rotated counter-clockwise & negative angles clockwise. Standard position has the initial side on the x-axis & the vertex on the origin.
Radians & the Unit Circle Radians are used to measure angles using arc length. Circumference: r = 1 180° = π 0° = 360° = 2π
Example #2Convert from Degrees to Radians 150° -330° 540°
Example #3Find the angle measures from each graph. 360° - 60°= 300° -360° + 90° + 115° = -155° 5(180°) = 900°
Example #4Draw the following angles in standard position. State the quadrant in which the terminal side is located. -110° 530°
Example #4Draw the following angles in standard position. State the quadrant in which the terminal side is located. 3400°
Example #4 (continued…)Draw the following angles in standard position. State the quadrant in which the terminal side is located.
Arc Length of a Circle Depending on whether an angle is given in radians or degrees the formulas for arc length vary slightly, although the concept remains the same. For radians: For degrees: The key to learning this is not to memorize either formula, but to build on what you already know. The length of an arc is a fraction of the distance around the entire circle (circumference). Multiply that fraction by the circumference of the circle and you get the arc length.
Sector Area of a Circle Depending on whether an angle is given in radians or degrees the formulas for sector area also vary. For radians: For degrees: And just like arc length, the formulas for sector area are based on the same concept:
Example #5 Find the Arc Length & Sector Area of the following: A.
Example #5 Find the Arc Length & Sector Area of the following: B.
Example #6Arc Length The second hand on a clock is 5 inches long. How far does the tip of the hand move in 45 seconds? 12 11 1 10 2 5’’ 9 3 4 8 7 5 6