DAY 09

Comment

One approach is to imagine cutting the kite along the 11 cm diagonal to form two identical triangles. The area of the triangles can be calculated if the base and height are known.

Answer

22 square centimetres.

Readers' methods

Janice Parlour, Lots Farm Cottage, Wells:
I changed the kite into an 11 cm by 2 cm rectangle:

Paul K, Wimbledon SW19:
Ler horizontal length 11 be divided by a and b, so a+b = 11.
The vertical length divides in two, ie 4 = 2+2.
Kite area = 2 x large triangles + 2 x small triangles
=2 x (a x 2 x 1/2) + 2 x (b x 2 x 1/2)
= 2 x a + 2 x b
= 2 x (a + b)
= 2 x 11
= 22.