7.
The diagram shows the quadrilateral \(A B C D\) in which \(A B = 6 \mathrm {~cm} , B C = 3 \mathrm {~cm}\), \(C D = 8 \mathrm {~cm} , A D = 9 \mathrm {~cm}\) and \(\angle B A D = 60 ^ { \circ }\).
- Show that \(B D = 3 \sqrt { 7 } \mathrm {~cm}\).
- Find the size of \(\angle B C D\) in degrees to 1 decimal place.
- Find the area of quadrilateral \(A B C D\).