Răspuns:
Explicație pas cu pas:
cosa=-2√2/3 sina=1/3 tga=1/3:(-2√2)/3=-1/2√2=-√2/4
cosb=1/5 sinb=-2√6/5 tgb=-2√6/5:1/5=-2√6
sin(a-b)=sinacosb-cosasinb=1/3×1/5-(-2√6/5)(-2√2/3)=1/15-4√3/15=
=(4√3-1)/15
cos(a+b)=-2√3/3×1/5-1/3(-2√6/5)=(-2√3+2√6)/16=-2√2(√3-1)/15
tg(a+b)=(tga+tgb)/(1-tgatgb)=(-√2/4-2√6)/(1-√2/4×2√6)=-√2(1/4+2√3)/(1-√3)=
=-√2(1+8√3)/4:(1-√3)=-√2(1+8√3)(1+√3)/4×(-2)=√2(25+11√3)/8
tg(a-b)=sin(a-b)/cos(a-b)=-2√2(1+√3)/15:-2√2(√3-1)/15=(√3+1)/(√3-1)
