Determinant of $$$\left[\begin{array}{cc}- 2 \sin{\left(2 t \right)} & 1\\- 4 \cos{\left(2 t \right)} & 0\end{array}\right]$$$
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Your Input
Calculate $$$\left|\begin{array}{cc}- 2 \sin{\left(2 t \right)} & 1\\- 4 \cos{\left(2 t \right)} & 0\end{array}\right|$$$.
Solution
The determinant of a 2x2 matrix is $$$\left|\begin{array}{cc}a & b\\c & d\end{array}\right| = a d - b c$$$.
$$$\left|\begin{array}{cc}- 2 \sin{\left(2 t \right)} & 1\\- 4 \cos{\left(2 t \right)} & 0\end{array}\right| = \left(- 2 \sin{\left(2 t \right)}\right)\cdot \left(0\right) - \left(1\right)\cdot \left(- 4 \cos{\left(2 t \right)}\right) = 4 \cos{\left(2 t \right)}$$$
Answer
$$$\left|\begin{array}{cc}- 2 \sin{\left(2 t \right)} & 1\\- 4 \cos{\left(2 t \right)} & 0\end{array}\right| = 4 \cos{\left(2 t \right)}$$$A