Show that the curves x2 - y2 = a2 and 2 xy = b2 cross at right angles.

Individual problems from throughout mathematics history, as well as articles that include problem sets for students.

Show that the curves x2 - y2 = a2 and 2 xy = b2 cross at right angles.

The highest point of the Andes is about 4 miles above sea level.

A square circumscribed about a given circle is double in area to a square inscribed in the same circle. True of false? Prove your answer.

Given a guest on horseback rides 300 li in a day. The guest leaves his clothes behind. The host discovers them after 1/3 day, and he starts out with the clothes.

In order to encourage his son in the study of arithmetic, a father agrees to pay him 8 pennies for every problem solved correctly and to charge him 5 pennies for each incorrect solution.

There is a round town 8000 feet in circumference.

A bridge is built across a river in 6 months by 45 men. It is washed away by the current. Required the number of workmen sufficient to build another of twice as much worth in 4 months.

The triangle ABC has a right angle at C. Show that 1/ED=1/AC+1/AB

How a translation of Peano's counterexample to the 'theorem' that a zero Wronskian implies linear dependence can help your differential equations students

Now there are six-headed four-legged animals and four-headed two-legged birds placed together.