11. Five squares are positioned as shown. The small square indicated has area 1.
What is the value of $h$ ?
A 3
B 3.5
C 4
D 4.2
E 4.5
Solution
C

Since the shaded square has area 1 , its side-length is 1 . Let the side-length of the square above the shaded square be $a$, as shown in the diagram.

Therefore the side-lengths of the other squares, going anti-clockwise, are $a+1, a+1+1=a+2$ and $a+2+1=a+3$. From the diagram, it can be seen that $1+a+3=a+h$ and hence the value of $h$ is 4 .