Given:
Ratio of the side lengths of two similar rectangular prisms is [tex]\dfrac{3}{5}[/tex].
To find:
The ratio of their areas.
Solution:
If two figures are similar then their areas are proportional to the squares of their corresponding sides.
[tex]\dfrac{A_1}{A_2}=\dfrac{s_1^2}{s_2^2}[/tex]
[tex]\dfrac{A_1}{A_2}=\left(\dfrac{s_1}{s_2}\right)^2[/tex] ...(i)
Where, [tex]A_1,A_2[/tex] are areas and [tex]s_1,s_2[/tex] are corresponding sides.
It is given that ratio of the side lengths of two similar rectangular prisms is [tex]\dfrac{3}{5}[/tex]. It means, [tex]\dfrac{s_1}{s_2}=\dfrac{3}{5}[/tex].
Using (i), we get
[tex]\dfrac{A_1}{A_2}=\left(\dfrac{3}{5}\right)^2[/tex]
[tex]\dfrac{A_1}{A_2}=\dfrac{3^2}{5^2}[/tex]
[tex]\dfrac{A_1}{A_2}=\dfrac{9}{25}[/tex]
Therefore, the ratio of their areas is [tex]\dfrac{9}{25}[/tex]. It is also written as 9:25.
