S=1/2*AB*AC*sinA
1/2*3*5*sinA=6;
sinA=(2*6)/(3*5)=12/15=0.8;
cosA=√(1-sin^2(A) = √1-(0.8)^2 =√ 1-0.64 = √0.36 = 3/5=0.6;
По теореме косинусов
BC^2=AB^2+BC^2-2*AB*BC*cosA
BC^2=3^2+5^2-2*3*5*0.6=9+25-18=16
BC=√16 = 4
ответ : BC = 4
S=1/2*AB*AC*sinA
1/2*3*5*sinA=6;
sinA=(2*6)/(3*5)=12/15=0.8;
cosA=√(1-sin^2(A) = √1-(0.8)^2 =√ 1-0.64 = √0.36 = 3/5=0.6;
По теореме косинусов
BC^2=AB^2+BC^2-2*AB*BC*cosA
BC^2=3^2+5^2-2*3*5*0.6=9+25-18=16
BC=√16 = 4
ответ : BC = 4