Prove that a triangle with sides of length 5, 5 and 6 has the same area as a triangle with sides of length 5, 5 and 8. Find other pairs of non-congruent isosceles triangles which have equal areas.

Four rods, two of length a and two of length b, are linked to form
a kite. The linkage is moveable so that the angles change. What is
the maximum area of the kite?

Quadrilaterals in a Square

Age 11 to 14 Challenge Level:

Algebraic:
Can you find the area of the yellow square?
Can you find the area of the yellow triangles?
Can you use this to find the red area?

Geometric:
Are there any extra lines you could draw?