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Calculați sin 15, cos 75, sin 105

Răspuns :

Sergiugun
sin(15)=sin(60-45)=sin60*cos45-sin45*cos60= rad(3)/2*rad(2)/2 - rad(2)/2*1/2=
=rad(5)/4 - rad(2)/4= [rad(6)-rad(2)]/4

cos(75)=cos(30+45) = cos30*cos45-sin30*sin45= rad(3)/2*rad(2)/2 - -1/2*rad(2)/2 = [rad(6)-rad(2)]/4

sin(105)= sin(60+45)=sin60*cos45+sin45*cos60= rad(3)/2*rad(2)/2+
+ rad(2)/2*1/2=rad(6)/4 + rad(2)/4 = [rad(6)+rad(2)]\4