To measure the area of an arbitrary two dimensional shape you will use a planimeter. To measure an area you could also just use a simple ruler depending on how big the area is.
1/2(bh)
Pi (3.141...) is used for circles, and circles only. You use it to find the area and circumfrence.
-- Find out the population of the area. -- Find out the area of the area. -- Divide the population by the area. The result is the population density of the area.
Pi is used to find the area and perimeter of a circle and the volume of a sphere, cylinder, and cone. Pi=3.14159265358979323846264338327950288419716939937510582097494459230781640628620899862803482534211706798214808651328230664709384460955058223172535940812848111745028410270193852110555964462294895493038196... That was 200 decimal places of Pi.
Spectrometer
An instrument that measures square centimeters is a planimeter. A planimeter is used to calculate the area of a two-dimensional shape by tracing its perimeter. Additionally, a ruler or a measuring tape can be used to measure the dimensions of a shape in centimeters, which can then be multiplied to find the area in square centimeters.
The best place to find used drums sets may be online, or at a used instrument store. You can visit one in your area and perhaps get used drums sets for a cheap price.
A compass is used to find your location in a forest
A Triple Beam Balance is used to find the mass of an object.
A violin can be used, but its effectiveness is limited.
Graduated cylinder
Pressure gauges.
A Planimeter.
You can find reliable musical instrument repair shops in your area by searching online, asking for recommendations from local musicians or music stores, or checking with professional music organizations for referrals.
radar
A triple beam balence
Graduated cylinder