How to prove the following equation:cos*2(180+x)+tan(x-180)sin(720-x)cosx=cos2x

asked 2017-04-13 08:15:18 -0600

I have tried solving it but I just can't get it right

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What does cos*2(180+x) mean ?

tmonteil gravatar imagetmonteil ( 2017-04-13 09:50:33 -0600 )edit

Let me guess:

equ = (cos(pi+x))^2 +tan(x-pi)*sin(4*pi-x)*cos(x) == cos(2*x)

bool(equ) yields True

ndomes gravatar imagendomes ( 2017-04-13 11:28:15 -0600 )edit

Well...

sage: E = cos(pi+x)^2 + tan(x-pi) * sin(4*pi-x)*cos(x)
sage: E.simplify_trig()
2*cos(x)^2 - 1

This is the half of the cake.

dan_fulea gravatar imagedan_fulea ( 2017-04-13 13:27:08 -0600 )edit