7-1

Review of 7-1

This week I'm going to do a review on lesson 7-1 since we've been doing trig review all week. In this lesson, we learn how to convert degrees to radians, radians to degrees, degrees to minutes and seconds, and minutes and seconds to degrees. We also learned how to find co-terminal angles.

- To convert degrees to radians: degrees x pi/180 (In the calc, you type degrees/180, and convert to a fraction, then put pi beside it.

- To convert radians to degrees: radians x 180/pi (Pi will cancel out)

- To covert degrees to minutes and seconds: For minutes, you take what is behind the decimal and multiply by 60. Once you get that answer, you take what is behind the decimal and multiply by 60 which will give you your seconds.

- To convert from minutes and seconds to degrees: degrees + min/60 + sec/3600

- To find a co-terminal angle: n +/- 360 degrees

Example 1:

a) convert 315 degrees to radians: 315 degrees x pi/180

= 7pi/4

b) convert -pi/2 to degrees: -pi/2 x 180/pi

= -90 degrees

c) convert 1.32 to degrees, minutes, and seconds: 1.32 x 180/pi

= 75.630 degrees

- .630 x 60 = 37.8 minutes

- .8 x 60 = 48 seconds

= 75 degrees, 37 minutes, 48 seconds

Example 2:

a) Find a positive co-terminal angle to -100 degrees: -100 + 360

= 260 degrees

b) Find a negative co-terminal angle to 500 degrees: 500 - 360(2)

= -220 degrees