The ratio of the areas of two triangle with common base =4:3
Height of the larger triangle (h1)=20 cm
Height of the smaller triangle (h2)=?
Area of larger triangleArea of smaller triangle=h1h2 ....[∵ triangles have common base]
⇒43=20h2
⇒h2=3×204=15 cm
∴ height of smaller triangle is 15 cm.