Answer
150 $cm^{2}$
Work Step by Step
sides of the triangle = 15 cm , 20cm , 25 cm.
by pythagoras Theorem $15^{2}$ +$20^{2}$ = $25^{2}$
HENCE its a Right angled Triangle
area of a right angled triangle =
$1\div$2 $\times $15 $\times $20 = 150 $cm^{2}$