How to prove the following equation:cos*2(180+x)+tan(x-180)sin(720-x)cosx=cos2x
 
  
 
 
     
 
 
 
 
 
 
 
    
        
        asked 7 years ago  
 
 Mbalienhle gravatar image  
 
 
 
 
 
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 (
    
        7 years ago
    )
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 (
    
        7 years ago
    )
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 (
    
        7 years ago
    )
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