El
Elmi
cos(15pi/2)-4sin(9pi)+2tg(7pi/6)=cos(7pi+pi/2)-4sin(9pi)+2tg(pi+pi/6)=cos(3pi/2)-4sin(9pi)+2tg(pi/6)=0-0+2*sqrt3/3=2sqrt3/3
cos(15pi/2)-4sin(9pi)+2tg(7pi/6)=cos(7pi+pi/2)-4sin(9pi)+2tg(pi+pi/6)=cos(3pi/2)-4sin(9pi)+2tg(pi/6)=0-0+2*sqrt3/3=2sqrt3/3
cos(15pi/2)-4sin(9pi)+2tg(7pi/6)=cos(7pi+pi/2)-4sin(9pi)+2tg(pi+pi/6)=cos(3pi/2)-4sin(9pi)+2tg(pi/6)=0-0+2*sqrt3/3=2sqrt3/3
15 пи/2=16 пи/2 - пи/2 = 8пи - пи/2
cos15п/2 =cos(8пи - пи/2)= cos (-пи/2)=cos пи/2=0
9пи=8пи+пи
sin9п=sin (8пи+пи) =sin пи=0
7пи/6=6пи/6+пи/6=пи+пи/6
tg7п/6=tg(пи+пи/6)=tg пи/6=1/√3
cos15п/2-4sin9п+2tg7п/6=0-0+2√3=2/√3