One side of a triangle is divided into segments of length a and b by the inscribed circle, with radius r. Prove that the area is: abr(a+b)/ab-r^2

Straight lines are drawn from each corner of a square to the mid points of the opposite sides. Express the area of the octagon that is formed at the centre as a fraction of the area of the square.

If you were to set the X weight to 2 what do you think the angle might be?

The third of three articles on the History of Trigonometry.

The second of three articles on the History of Trigonometry.

The first of three articles on the History of Trigonometry. This takes us from the Egyptians to early work on trigonometry in China.

How far should the roof overhang to shade windows from the mid-day sun?

Six circular discs are packed in different-shaped boxes so that the discs touch their neighbours and the sides of the box. Can you put the boxes in order according to the areas of their bases?

From the measurements and the clue given find the area of the square that is not covered by the triangle and the circle.

An environment that simulates a protractor carrying a right- angled triangle of unit hypotenuse.

Without using a calculator, computer or tables find the exact values of cos36cos72 and also cos36 - cos72.

The sides of a triangle are 25, 39 and 40 units of length. Find the diameter of the circumscribed circle.

The area of a regular pentagon looks about twice as a big as the pentangle star drawn within it. Is it?

You are given a circle with centre O. Describe how to construct with a straight edge and a pair of compasses, two other circles centre O so that the three circles have areas in the ratio 1:2:3.

Draw three equal line segments in a unit circle to divide the circle into four parts of equal area.

The coke machine in college takes 50 pence pieces. It also takes a certain foreign coin of traditional design...

Use simple trigonometry to calculate the distance along the flight path from London to Sydney.

Re-arrange the pieces of the puzzle to form a rectangle and then to form an equilateral triangle. Calculate the angles and lengths.

Three points A, B and C lie in this order on a line, and P is any point in the plane. Use the Cosine Rule to prove the following statement.

What angle is needed for a ball to do a circuit of the billiard table and then pass through its original position?

A moveable screen slides along a mirrored corridor towards a centrally placed light source. A ray of light from that source is directed towards a wall of the corridor, which it strikes at 45 degrees. . . .

Prove that the shaded area of the semicircle is equal to the area of the inner circle.

Two perpendicular lines lie across each other and the end points are joined to form a quadrilateral. Eight ratios are defined, three are given but five need to be found.

It is obvious that we can fit four circles of diameter 1 unit in a square of side 2 without overlapping. What is the smallest square into which we can fit 3 circles of diameter 1 unit?

What is the longest stick that can be carried horizontally along a narrow corridor and around a right-angled bend?