Given data:
The hypotenuuse of the triangle is H=25 cm.
The base of the triangle is B=20 cm.
The expression for the Pythagoras theorem is,
[tex]H^2=P^2+B^2[/tex]Substitute the given values in the above expression.
[tex]\begin{gathered} (25cm)^2=P^2+(20cm)^2 \\ P^2=625cm^2-400\operatorname{cm} \\ P=15\text{ cm} \end{gathered}[/tex]Thus, the other side of the triangle is 15 cm.