### Areas and Ratios

Do you have enough information to work out the area of the shaded quadrilateral?

### Shape and Territory

If for any triangle ABC tan(A - B) + tan(B - C) + tan(C - A) = 0 what can you say about the triangle?

### Napoleon's Hat

Three equilateral triangles ABC, AYX and XZB are drawn with the point X a moveable point on AB. The points P, Q and R are the centres of the three triangles. What can you say about triangle PQR?

# Middle Man

##### Age 16 to 18Challenge Level

Try rotating the chord through $P$ by $360^\circ$. What happens to the length of this chord?