Chapter 10 is formula after formula and the trig chart has come back to haun-I mean prove its usefullness. I am going to talk about the formulas from 10-1. Here we go.
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
EXAMPLE :D
Find the exact value of sin75degrees.
sin(45degrees+30degrees)=sin45cos30-cos45sin30
45degrees is alpha and 20 degrees is beta. I simply plugged it in to equation 2.
That's the way you do that. Have a happy Halloween :D
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