1.1. Show that each interior angle of a regular pentagon is $108^{\circ}$. 

The diagram shows a regular pentagon $ABCDE$.
The vertices of the pentagon lie on a circle, centre $O$, radius $12\text{cm}$.
$M$ is the midpoint of $BC$.

i) Find $BM$.  

$BM$ = ........................................ cm [3]

$OMX$ and $ABX$ are straight lines.

iia) Find $BX$.   

$BX$ = ........................................ cm [3]

iib) Calculate the area of triangle $AOX$.   

........................................ cm² [3]