Example J.1: Area of a table

If our table is 1.80 m in length and 1.20 m in width and has the shape of a rectangle, what is its area? We might want to paint the top of the table, and need to know its area to figure out how much paint we need.

Solution

First we write down what we know, giving it names that remind us what the values are about:

\(L_{\mathrm{table}}\) \(= 1.80\ \mathrm{m}\)


\(W_{\mathrm{table}}\) \(= 1.20\ \mathrm{m}\)


Then we write down what we are planning on calculating. Here, it is the area of the table, \(A_{\mathrm{table}}\)
\(A_{\mathrm{table}}\) = ?


Now we make a plan. The area \(A\) of a rectangle is equal to its length \(L\) times its width \(W\) . The formula would be:

\(A = L \cdot W\)     

Finally, we can ask PQcalc to do the calculation for us:

\(A_{\mathrm{table}}\) \(= L_{\mathrm{table}} \cdot W_{\mathrm{table}}\)

\(\ \ \ =1.80\ \mathrm{m} \cdot 1.20\ \mathrm{m}\)

\(\ \ \ =2.16\ \mathrm{m}^{2}\)


The table has an area of 2.16 square meters.