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Calucati : sin15° • cos 75° +cos^2 165° = ?

Răspuns :

sin15·cos 75 = [ sin 90 +sin60]/ 2  = ( √3/2 +1) /2= ( √3 +2) /4
cos²165= cos 165·cos165 = [cos 330 +cos 0 ]/2= ( √3/2 +1) /2= ( √3 +2) /4 
rezultat final = (√3+2) /2