Determine an equation of $L$ in coordinate form and the angle $\varphi$ that $L$ makes with the $x _ { 1 } x _ { 2 }$-plane. (for verification: $x _ { 1 } + x _ { 2 } + x _ { 3 } - 19 = 0 ; \varphi \approx 55 ^ { \circ }$ )
Determine an equation of $L$ in coordinate form and the angle $\varphi$ that $L$ makes with the $x _ { 1 } x _ { 2 }$-plane.\\
(for verification: $x _ { 1 } + x _ { 2 } + x _ { 3 } - 19 = 0 ; \varphi \approx 55 ^ { \circ }$ )