Show that the area of the large square in the diagram can be written as (x+y)², and..

Show that the area of the large square in the diagram can be written as (x+y)², and also as z²+2xy?


HERE IS THE DIAGRAM http://img43.imageshack.us/img43/9428/trig.png

Do not use pythagoras theorem.

b) Show how these results can be used to prove pythagoras theorem

The side of the larger square is x+y

Hence area of the large square=

Thanks. How do I Show how these results can be used to prove pythagoras theorem

and also how do i show it can be written as z²+2xy?

Inside the larger square,
there is a square of side z, and four right triangles of side x,y.

total area=square of side z+4*area of triangles
=
=

pythagoras theorem: press spoiler

Spoiler: