Răspuns:
Explicație pas cu pas:
tg 75=sin (30+45)/cos(30+45)
sin (30+45)=sin 30cos45+cos30sin 45=1/2×√2/2+√3/2×√2/2=
=√2/2(1/2+√3/2)=√2(1+√3)/4
cos(30+45)=cos30c0s45-sin30sin45=√3/2×√2/2-1/2×√2/2=
√2/2(√3-1)/2=√2(√3-1)/4
tg 75=(√3+1)/(√3-1)
tg 75+tg 75=2(√3+1)/(√3-1)