Pre-Cal 40S (Winter 2009): BOB for identities..

Monday, April 6, 2009

BOB for identities..

One more unit is done... so i just go straight forward ...

In this unit, most we do are about sine and cosine.

Remember:

from that equation, we can easily get these implies by dividing both side by

and we get :

then we studied about the sum and difference identities

$cos(\alpha-\beta) = cos\alpha cos\beta + sin\alpha sin\beta$

$cos(\alpha+\beta) = cos\alpha cos\beta - sin\alpha sin\beta$

$sin(\alpha-\beta) = sin\alpha cos\beta - cos\alpha sin\beta$

$sin(\alpha+\beta) = sin\alpha cos\beta + cos\alpha sin\beta$

since we got that, we'd know the expression for sin2x , cos2x, and tan2x

I don't think i got any problem with this unit and all thing below i think are the main idea of this unit.

Pre-test is tomorrow, Tue, April 7
Test is on Thu, April 9.

Good luck all ..