If the volume of the tetrahedron formed by the coterminous edges $\mathbf{a}, \mathbf{b}$ and $\mathbf{c}$…

If the volume of the tetrahedron formed by the coterminous edges $\mathbf{a}, \mathbf{b}$ and $\mathbf{c}$ is 4 , then the volume of the parallelopiped formed by the coterminous edges $\mathbf{a} \times \mathbf{b}, \mathbf{b} \times \mathbf{c}$ and $\mathbf{c} \times \mathbf{a}$ is
  1. 576
  2. 48
  3. 16
  4. 144

Solution

As we know, the volume of tetrahedron formed by the coterminous edges $\mathbf{a}, \mathbf{b}$ and $\mathbf{c}$, $ \begin{aligned} & V=\frac{1}{6}\left[\begin{array}{lll} \mathbf{a} & \mathbf{b} & \mathbf{c} \end{array}\right] \\ & 4=\frac{1}{6}\left[\begin{array}{lll} \mathbf{a} & \mathbf{b} & \mathbf{c} \end{array}\right] \end{aligned} $
Now, the volume of parallelopiped formed, by the coterminous edges $\mathbf{a} \times \mathbf{b}, \mathbf{b} \times \mathbf{c}$ and $\mathbf{c} \times \mathbf{a}$. $ \begin{aligned} \mathrm{V} & =\left[\begin{array}{lll} \mathbf{a} \times \mathbf{b} & \mathbf{b} \times \mathbf{c} & \mathbf{c} \times \mathbf{a} \end{array}\right] \\ \mathrm{V} & =\left[\begin{array}{lll} \mathbf{a} & \mathbf{b} & \mathbf{c} \end{array}\right]^2 \\ \mathrm{~V} & =(24)^2=576 \quad(\text { from Eq. (i)) } \end{aligned} $

Asked in: AP EAMCET 2017 (26 Apr Shift 1)

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