1. ## Half Angle Fromula

If t = tan1/2Ø

Then show that:

sinØ = 2t/1+t^2

I have deduced that:

sin2A=2tanA/1+tan^2A

But am unsure how to get from the second formula to the first.

2. ## Re: Half Angle Fromula

Hey KiaraG16.

Hint - Let A = 1/2.

3. ## Re: Half Angle Fromula

Oh I see, so because A could equal any angle it could also equal 1/2*Theta which is why the second equation remains the same as the first?

4. ## Re: Half Angle Fromula

That's basically the idea.