#### 3.1 Angles in the Coordinate Plane terminal side Positive initial side Negative We can measure angles in degrees once around Ex 1) Find the degree measure of.

download report#### Transcript 3.1 Angles in the Coordinate Plane terminal side Positive initial side Negative We can measure angles in degrees once around Ex 1) Find the degree measure of.

### 3.1 Angles in the Coordinate Plane

terminal side Positive initial side Negative We can measure angles in degrees 360 once around

Ex 1) Find the degree measure of the angle for each given rotation & draw angle in standard position.

a) rotation clockwise 3 2 = –240° 3 11 b) rotation counterclockwise 6 11 6 = 660°

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 b) 50.525

5 40 in decimal places 1 40 60 1 3600 40.668

in deg-min-sec .525

60 31.5

31 .5

60 31 30 50 31 30

Ex 3) Identify all angles coterminal with –450 coterminal angle whose measure is between 0 & find the & 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?

18h 360 12 h = 540°

Ex 5) What is the measure in degrees of the smaller of the angles formed by the hands of a clock at 6:12?

72° long hand (minute) at :12 so each minute is 360 60 = 6° from 12:00 12(6 ) = 72° short hand (hour) is not right at 6!

**6° 180° – 72° = 108°**

12 1 It is of the way to 7 60 5 1 Between hour 6 and hour 7 is 12 108° + 6° = 114° so… 1 5 6 30

### Homework

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