Find the angle between the pairs of lines with direction ratio proportional to: `a ,\ b ,\ c\ a n d\ b-c ,\ c-a ,\ a-bdot`

Explanation

`cos theta=frac{-a_{1} a_{2}}{sqrt{a_{1}^{2}+b_{1}^{2}+c_{1}^{2}}+b_{a_{2}}{ }^{2}+b_{2}^{2}+c^{2}}`

`a_{1} a_{2}^{2}+b_{1} b 2+c_{1} c 2=q b^{2}-a / c+b / c-b / a+4 a-c p`

`cos theta=0`

`cos theta=cos 90^{circ}`

`theta=90^{circ}`