3.1 Angles in the Coordinate Plane

1. 3.1 Angles in the Coordinate Plane

2. terminal side Positive  Negative initial side  We can measure angles in degrees 360  once around

3. Ex 1) Find the degree measure of the angle for each given rotation & draw angle in standard position. a) rotation clockwise = –240° b) rotation counterclockwise = 660°

4. Degrees  Minutes  Seconds 60 minutes in 1 degree / 60 seconds in 1 minute 1 = 60 = 3600 * to figure out which ratio, think about what you are canceling – put that on bottom of fraction Ex 2) Express: a) 4040 5 in decimal places b) 50.525 in deg-min-sec

5. Ex 3) Identify all angles coterminal with –450 & find the coterminal angle whose measure is between 0 & 360 –450 + 360°k (k is an integer) –450 + 360° = –90° –450 + 720° = 270° Horology (having to do with time) Ex 4) The hour hand of the clock makes 1 rotation in 12 hours. Through how many degrees does the hour hand rotate in 18 hours? = 540°

6. Ex 5) What is the measure in degrees of the smaller of the angles formed by the hands of a clock at 6:12? long hand (minute) at :12 so each minute is = 6° 72° • from 12:00 • 12(6) = 72° short hand (hour) is not right at 6! It is of the way to 7 6° 180° – 72° = 108° • Between hour 6 and hour 7 is • so… 108° + 6° = 114°

7. Homework #301 Pg 123 #1, 5, 7, 9, 15–31 odd, 32–39, 41, 43, 45, 47