Выходит так:
AB=34
Угол C = 90 Градусам
tgA=4
AH = ?
AH = AC * cos(A)
Найдем cos A
cos(a) = sqrt (1/(1+tg(a)^2))
cos(a) = sqrt (1/(1+4^2))
cos(a) = 1/sqrt(17)
Найдем AC
AC = cos(A)*AB
AC= 1/sqrt(17) * 34
AC = 34/sqrt(17)
Находим AH
AH = AC * cos(A)
AH = 34/sqrt(17) * 1/sqrt(17)
AH = 34/sqrt(289)
AH = 34/17
AH = 2