10-1

soooo I left my binder at school friday because I was too worried about getting out of that stupid, but educational, building that consist of dull colors and smelly children. Sooo im going to wing it. I have all the formulas on a notecard so i think that will help a little bit.

So here it goes, im going to show you all of the formulas then i might work a few problems.

1. cos(alpha+/-beta)=cosalphacosbeta-/+sinalphasinbeta

2. sin (alpha+/-beta)=sinalphacosbeta+/-cosalphasinbeta

3. sinx+siny=2sinx+y/2 cosx-y/2

4. sinx-siny=2cosx+y/c sin x-y/2

5. cosx+cosy=2cosx+y/2cosx-y/2

6.cosx-cosy=-2sinx+y/2 sinx-y/2

Soo now that i have showed you the formulas im going to give you 2 examples. Make sure you follow closely cause im only going to show you how to do it once!

Ex1. a) cos 120 cos 30 + sin 120 sin 30=
cos (120 - 30)=
cos (90)=
0

Ex2. a) sin70 cos20 + cos70 sin20
sin(70+20)=
sin(90)
1

love yours truely <3