cos a = AC/AB=4/5 => AB=5
по теореме Пифагора
BC^2+AC^2=AB^2
BC= sqrt ( AB^2-AC^2)
BC = 3
S= 1/2 * CH*AB
CH=2*S/AB
S=1/2*BC*AC=3*4/2=6
CH=2*6/5=2,4
cos a = AC/AB=4/5 => AB=5
по теореме Пифагора
BC^2+AC^2=AB^2
BC= sqrt ( AB^2-AC^2)
BC = 3
S= 1/2 * CH*AB
CH=2*S/AB
S=1/2*BC*AC=3*4/2=6
CH=2*6/5=2,4