$$\left| \overrightarrow c \right| = \left| \begin{pmatrix} 2\\-2 \end{pmatrix} \right| = \sqrt{2^2 + 2^2} = \sqrt{8} = 2 \cdot \sqrt{2} \newline \left| \overrightarrow d \right| = \left| \begin{pmatrix} 7\\8\\9 \end{pmatrix} \right| = \sqrt{7^2 + 8^2 + 9^2} = \sqrt{194}$$