The areas of two similar triangles $ABC$ and $DEF$ are $64 {\mathrm{cm}}^2$ and $169 {\mathrm{cm}}^2$ respectively. If the length of $BC$ is $4 \mathrm{cm}$, find the length of $EF$.

In the figures, $△ABC~△PQR$. Also area $\left(△ABC\right)=4.$area $\left(△PQR\right)$. If $BC=12 \mathrm{cm}$, find $QR$.

The areas of two similar triangles $ABC$ and $DEF$ are $64 {\mathrm{cm}}^2$ and $121 {\mathrm{cm}}^2$ respectively. If $EF=13.2 \mathrm{cm}$, find $BC$.

In the given figure, triangles $ABC$ and $DEF$ are similar. If area of $△ABC=49 {\mathrm{cm}}^2$, and area of $△DEF=64 {\mathrm{cm}}^2$ and $AC=4.8 \mathrm{cm}$, find $DF$.

The areas of two similar triangles are $81 {\mathrm{cm}}^2$ and $49 {\mathrm{cm}}^2$ respectively. If the altitude of the bigger triangle is $4.5 \mathrm{cm}$, find corresponding altitude of the smaller triangle.

The areas of two similar triangles are $100 {\mathrm{cm}}^2$ and $49 {\mathrm{cm}}^2$ respectively. If the altitude of the bigger triangle is $5 \mathrm{cm}$, find corresponding altitude of the other.

The areas of two similar triangles are $81 {\mathrm{cm}}^2$ and $49 {\mathrm{cm}}^2$ respectively. If the altitude of the first triangle is $6.3 \mathrm{cm}$, find corresponding altitude of the other.