10.
$$\mathbf { A } = \left( \begin{array} { c c }
3 \sqrt { } 2 & 0
0 & 3 \sqrt { } 2
\end{array} \right) , \quad \mathbf { B } = \left( \begin{array} { c c }
0 & 1
1 & 0
\end{array} \right) , \quad \mathbf { C } = \left( \begin{array} { c c }
\frac { 1 } { \sqrt { } 2 } & - \frac { 1 } { \sqrt { } 2 }
\frac { 1 } { \sqrt { } 2 } & \frac { 1 } { \sqrt { } 2 }
\end{array} \right)$$
- Describe fully the transformations described by each of the matrices \(\mathbf { A } , \mathbf { B }\) and \(\mathbf { C }\).
It is given that the matrix \(\mathbf { D } = \mathbf { C A }\), and that the matrix \(\mathbf { E } = \mathbf { D B }\).
- Find \(\mathbf { D }\).
- Show that \(\mathbf { E } = \left( \begin{array} { c c } - 3 & 3
3 & 3 \end{array} \right)\).
The triangle \(O R S\) has vertices at the points with coordinates \(( 0,0 ) , ( - 15,15 )\) and \(( 4,21 )\). This triangle is transformed onto the triangle \(O R ^ { \prime } S ^ { \prime }\) by the transformation described by \(\mathbf { E }\). - Find the coordinates of the vertices of triangle \(O R ^ { \prime } S ^ { \prime }\).
- Find the area of triangle \(O R ^ { \prime } S ^ { \prime }\) and deduce the area of triangle \(O R S\).