The angle between the lines whose direction ratios are proportional to

1.	The angle between the lines whose direction ratios are proportional to a, b, c and 1bc, 1ca, 1ab is _________________.
Answer» The angle between the lines whose direction ratios are proportional to a, b, c and $\frac{1}{b c}, \frac{1}{c a}, \frac{1}{a b}$ is _________________.

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