Draw a square of side $6 \mathrm{cm}$. Draw another square whose area is double the area of the first.

The two line segments $AB$ and $CD$ meet at $P$. Mention the three points through which a circle cannot be drawn.

$ABCD$ is a cyclic quadrilateral. If $\angle BDC=30°$ and $\angle ABC=100°$ and $\angle ACB=k°$, then find the value of $k$.