Help trig urgent

Help I was gonna ask… what did equals in double angle formulais it 2sin2theta?


And also for this q…
I dint get how to do it… this is what I’ve got so far but I’m super stuck 😭 I’ve gon my final a levels in 5days
it’s part V I’m stuck on

sin4x = 2sin2xcos2x

is this sin4theta?

if so, use sin(A+B) = SinACosB + SinBCosA

using A and B both 2 theta. Using that, you should get:
2Sin(2theta)Cos(2theta)


Use the same trick again with sin, but for Cos, use Cos(A+B) = SinACosA + SinBCosB, taking A and B both as Theta.

Now You should be able to simplify it further.

Hope this helps!

Do I take the two out to the front like this
2sin(2theta) ?

no. 4sinx = 2sin2xcos2x. then you can do double angle formula on the sin2x and cos2x

Is this just a rule im meant to know or can I work this out becaus I don’t get it

Is this just a rule im meant to know or can I work this out becaus I don’t get it