Sec 5.3 Sum­Difference Identities cos (u ­ v) = cos u cos ...

PC sec 5.3 notes.notebook

January 30, 2017

Sec 5.3 SumDifference Identities

cos (u v) = cos u cos v + sin u sin v cos (u + v) = cos u cos v sin u sin v

These are used when the trig angle can't be found on the Unit Circle.

Find the exact value of cos15? w/o calculator.

cos 15? =

1st: find 2 angles on unit circle which add or subtract to equal 15?

2nd: determine which formula to use based on whether you added or subtract the degrees.

3rd: look up each trig degree

on Unit circle

last: multiply square roots, then add to get one fraction

sin (u ? v) = sin u cos v ? cos u sin v

Before starting: change radians to degrees

1st: find 2 angles on unit circle which add or subtract to equal 15?

2nd: determine which formula to use based on whether you added or subtract the degrees. 3rd: look up each trig degree on Unit circle

last: multiply square roots, then add to get one fraction

1

PC sec 5.3 notes.notebook

Working backwards

ex. sin 22 cos 13 + cos 22 sin 13

January 30, 2017

ex. sinx sin 2x cos x cos 2x

Assignment: MyMathLab sec 5.3

sin (u ? v) = sin u cos v ? cos u sin v

cos (u v) = cos u cos v + sin u sin v

2

PC sec 5.3 notes.notebook

January 30, 2017

3

 ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download