Question

two vectors of magnitute 20cm and 10cm make angles of 120 and 50 with Xaxis inthe XY PLANE FIND THEIR CROSS PRODUCT

Answer 1

$$\vec{a}\times\vec{b}=\begin{vmatrix} i & j & k \\ 20\cos{120} & 20\sin{120}& 0 \\ 10\cos{50} & 10\sin{50}& 0 \end{vmatrix}\\=((20\cos{120})(10\sin{50})-(20\sin{120})(10\cos{50}))\vec{k}\\=(-188\vec{k})\ cm^2$$