# The volume of the tetrahedron having the edges $\overrightarrow {i}+2 \overrightarrow {j}-\overrightarrow {k},\overrightarrow {i}+\overrightarrow {j}+ \overrightarrow {k},\overrightarrow {i}+\overrightarrow {j}+ \lambda \overrightarrow {k}$ as coterminous, is $\large\frac{2}{3}$ cubic units. Then $\lambda=$

$\begin {array} {1 1} (1)\;1 & \quad (2)\;2 \\ (3)\;3 & \quad (4)\;4 \end {array}$

(1) 1
answered Nov 7, 2013 by