A5 A right triangle has an area of $24 \mathrm{~cm}^{2}$, the sides of the triangle are in the ratio $0.24: 0.32: 0.4$. The perimeter of this triangle is:
(A) $12 \mathrm{~cm}$
(B) $16 \mathrm{~cm}$
(C) $20 \mathrm{~cm}$
(D) $24 \mathrm{~cm}$
(E) $25 \mathrm{~cm}$
A5. We note that $a=0.24 x, b=0.32 x$ and $c=0.4 x$. The area of the triangle is $\frac{a \cdot b}{2}=24$. Substituting $0.24 x \cdot 0.32 x=48$, we calculate $x=5$. We then calculate $a=6 \text{ cm}, b=8 \text{ cm}$ and $c=10 \text{ cm}$, so the perimeter is $24 \text{ cm}$.