# Math Help - trig identities

1. ## trig identities

a stands for alpha b stands for beta

a)cos(a+b)= b)2cos squared a - 1=

c)tan2a= d)sin1/2theta=

e) sin a =
1+ cos a

2. Originally Posted by Dave19
a stands for alpha b stands for beta

a)cos(a+b)= b)2cos squared a - 1=

c)tan2a= d)sin1/2theta=

e) sin a =
1+ cos a
For a) - d) use the link I gave in your other thread.

For e) what are you looking for? This is
$\frac{sin(a)}{1 + cos(a)}$
right? There are any number of equivalent forms that we might create from this. I'm not sure which one you would be looking for?

-Dan