Use a model for body surface area, BSA, such that $BSA=\sqrt{\frac{wh}{3600}}$, where $w=$ weight in $\mathrm{kg}$ and $h=$ height in $\mathrm{cm}$.
Find the weight of a $175-\mathrm{cm}$ male to the nearest $\mathrm{kg}$ whose $BSA=2.1$.

Step 1 ：We are given a model for body surface area (BSA) such that $BSA=\sqrt{\frac{w\times h}{3600}}$, where $w$ is the weight in kg and $h$ is the height in cm.

Step 2 ：We are asked to find the weight of a 175 cm male whose BSA is 2.1. We can rearrange the formula to solve for weight. The rearranged formula would be $w=\frac{BS{A}^2\times 3600}{h}$.

Step 3 ：Substitute the given values into the formula to find the weight. Where BSA = 2.1 and h = 175.

Step 4 ：By substituting the values into the formula, we get $w=\frac{(2.1{)}^2\times 3600}{175}$.

Step 5 ：Solving the above expression, we find that $w\approx 91$.

Step 6 ：Final Answer: The weight of a 175-cm male whose BSA is 2.1 is approximately $\boxed{{\displaystyle 91}}$ kg.