fat mass
Go to your local gym. they will have body composition scales which test composition by electrical resistance in your body. They are also traines in skin fold techniques which is also pretty accurate.
Uranium to lead ratios are most often used to date rocks but I would not call it absolute determinations
The body composition is a series of tests used to compare the proportion of fat mass to lean mass. Fat mass is defined is the essential fats plus the stored fats.
The ratios are percents, which can be calculated by a punnett square.
oxygen
There are no ratios that can be used for triangles that are not similar.
The BMI score is usually based on two numbers: your height and your weight. Some formulas may include additional variables, such as the circumference of your wrist or neck. Still, these are just numbers and the result calculated on their basis may be inaccurate. The BMI score can be used as one of the indicators of body composition, but it should not be treated as the main indicator. Your body fat percentage is a more exact indicator of your body composition.
Ratios are used to compare numbers. When you're working with ratios, it's sometimes easier to work with an equivalent ratio.
what is market to book ratios used for?
Most likely a surgeon needs to be able to do basic trigonometry and arithmetic in order to make sure that ratios between body parts are correct and that joints have the proper angles to maintain proper body function. On top of this they may also need to be able to determine volumes of certain shapes when transplanting body tissue from one part of a body to the other.
Generally the composition is 10 % methanol and 90 % ethanol.