Alina8faq

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7 years, 212 days

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These are questions asked by Alina8faq

I have some difficulties in my little example:

K:=(Itr*sin(a+b)2-Itrsin(a-b)2)/(Itr*sin(a+b)2+Itrsin(a-b)2)+2*Iex

... after few transformations ...

K:=sin(2a)sin(2b)/(sin(a)2cos(b)2+cos(a)2sin(b)2+Iex/Itr)

also we have:

r:=Iex/Itr

d:=1+2*r

My question is in the title, here is simple example: 

K:=(sin^2(a+b)-sin^2(a-b))

I use formula of abridged multiplication (with help of "factor")

>factor(K)

  (sin(a+b) - sin(a-b))(sin(a+b) + sin(a-b))

Then expand:

>expand(%, trig)

  4sin(a)cos(b)cos(a)sin(b)

And all I whant now is to use double angle formula like this:

4sin(a)cos(b)cos(a)sin(b) = sin(2a)sin(2b)

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