Am I correct on these? I selected two answers as true, but I'm not sure if there's a third true answer provided.

Question

anonymous · Answer

attachment

anonymous · Answer

I know the second option is false, but what about the third statement, C?

anonymous · Answer

it is also true :)

dumbcow · Answer

third statement is true as well

dumbcow · Answer

try it out yourself, prove it works

anonymous · Answer

Okay, awesome! Thank you guys (: I wasn't sure, in my text book it said that it can be derived from sum identities but didn't say anything about (A + A) or (A + B)

anonymous · Answer

it happens like this, sin(a+b)=sinacosb+cosasinb
put b=a, so sin(a+a)=sinacosa+sinacosa
sin2a=2sinacosa

anonymous · Answer

OOH! That makes sense (: Lol

anonymous · Answer

and for cos2a, try yourself :)

anonymous · Answer

Okie dokie (: Thank you for the help and pointers! :D