Найдем sinA=sqrt(1- cos^2(A)) = sqrt(1-(5/9))= sqrt(4/9) = 2/3
По определению sinA = BC/AB, 2/3 = 4/AB, AB = (4*3)/2 = 6
Найдем sinA=sqrt(1- cos^2(A)) = sqrt(1-(5/9))= sqrt(4/9) = 2/3
По определению sinA = BC/AB, 2/3 = 4/AB, AB = (4*3)/2 = 6