Area of triangle with a,b,c as sides and
s=a+b+c2 is √s(s−a)(s−b)(s−c) .
For triangle with sides 18 cm, 24 cm and 30 cm, s=18+24+302=36cm
Area of the triangle with sides 18cm,24cm and 30cm=√36(36−18)(36−24)(36−30)
=√36×18×12×6
=√18×2×18×6×2×6
=18×6×2
=216cm2
Let the height for base 30cm, be h
Area of triangle =12×base×height=216cm2
⇒12×30×h=216
⇒h=14.4cm