posted by Bailey .
I can't remember what formula to use for these.
Note- the X's may be replaced by a theta symbol. I just didn't have one on my keyboard.
Use the given information to find sin2X, cos2X and tan2X if 0< X <pi/2
You use the double angle formulas.
To type θ, you need to type the following without the double quotes nor the spaces: "& t h e t a ;".
As Diana suggested, use the double angle formulas. I'll do the first one as an example.