[tex]\begin{gathered} \text{The area of a triangle = }\frac{1}{2}\times base\times perpendicular\text{ height} \\ \text{either legs can be the base or perpendicular height, since the triangle is right angled} \\ \text{Hence,} \\ \text{the area = }\frac{1}{2}\times6\times5=15\operatorname{cm} \\ \text{option B} \end{gathered}[/tex]