A round pond sits in a rectangular garden. Its center is inaccessible; however, you know the distances from each corner of the garden to the center of the pond: 60, 52, 28, and 40 yards. What is the radius of the pond?
This is the title page to the English version of Isaac Barrow's Geometrical Lectures, which were originally given in his position as Lucasian Professor of Mathematics at Cambridge University. These lectures contain one of the earliest statements and proofs of what is today known as the fundamental theorem of calculus.
A carpenter has undertaken to build a house in 20 days. He takes on another man and says; "If we build the house together, we can accomplish the work in 8 days!" How long would it take this other man to build the house working alone?