12.2 – angles and angle measure. standard position – when the vertex of the angle is at the...
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12.2 – Angles and Angle Measure
Standard Position – when the vertex of the angle is at the origin and one ray is on the positive x-axis.
Initial Side – the ray on the x-axis.(where the angle starts.)
Terminal Side - the ray that rotates about the center. (where the angle ends.)
Example 1:Draw an angle with the given measure in standard position.
a. 210°b. –45°
Example 2:a. In a springboard diving competition, a diver made a 900-degree rotation before slicing into the water. Draw an angle in standard position that measures 900°.
Example 2:b. While riding down the mountain, a snowboarder goes off a jump and turns 600° before touching down onto the snow again. Determine how many degrees past the positive x-axis the snowboarder lands.
Coterminal Angles:- Two or more angles in standard position
with the same terminal side.
- How can we find coterminal angles???
Example 3:Find an angle with a positive measure and an angle with a negative measure that are coterminal with each angle.
b. 210°b. –120°
Radians:- Units that are based on arc length.- The measure of an angle in standard
position with a terminal side that intercepts an arc with the same length as the radius of the circle.
- radians = 360- So how many degrees is radians?
Example 4: Conversionsa. Rewrite 30° in radians.
b. Rewrite 120° in radians.
Example 5: Conversions
a. Rewrite in degrees.
b. Rewrite in degrees.
- Central Angle – an angle with a vertex at the center of the circle.
Example 6:a. The steering wheel on a monster truck has a radius of 11 inches. How far does a point on the steering wheel travel if the wheel makes four fifths of a rotation?
Example 6:b. The steering wheel on a yacht has a radius of 16 inches. How far does a point on the steering wheel travel if the wheel makes five sevenths of a rotation?