Explanation:

area of triangle=1176
ratio of base to height=3:4
let base=3x
and height =4x
the area of triangle=1/2×base×height
=1/2×3x×4x
=6x^2
1176=6x^2
1176/6=x^2
196=x^2
14^2=x^2
14=x

base =3x=3×14 =42
height(altitude)=4x
=4×14 = 56

Hence, option 4 is the correct answer.