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Vector Algebra

Question
CBSEENMA12034244

If straight a with rightwards arrow on top cross times straight b with rightwards arrow on top space equals straight a with rightwards arrow on top cross times straight c with rightwards arrow on top and  straight a with rightwards arrow on top space not equal to space 0 with rightwards arrow on top comma then straight b with rightwards arrow on top space equals space straight c with rightwards arrow on top space plus space straight lambda space straight a with rightwards arrow on top, where straight lambda is a scalar.

Solution

   straight a with rightwards arrow on top space cross times space straight b with rightwards arrow on top space equals space straight a with rightwards arrow on top cross times straight c with rightwards arrow on top space space space rightwards double arrow space space space space straight a with rightwards arrow on top space cross times space straight b with rightwards arrow on top space space minus straight a with rightwards arrow on top space cross times space straight c with rightwards arrow on top space equals space 0 with rightwards arrow on top
rightwards double arrow space space space straight a with rightwards arrow on top space cross times space open parentheses straight b with rightwards arrow on top space minus space straight c with rightwards arrow on top close parentheses space equals space 0 with rightwards arrow on top space space space space space rightwards double arrow space space space space straight b with rightwards arrow on top minus straight c with rightwards arrow on top space is space parallel space to space straight a with rightwards arrow on top
rightwards double arrow space space space space straight b with rightwards arrow on top space minus space straight c with rightwards arrow on top space equals space straight lambda space straight a with rightwards arrow on top space space space space rightwards double arrow space space space straight b with rightwards arrow on top space equals space straight c with rightwards arrow on top space plus space straight lambda space straight a with rightwards arrow on top comma space where space straight lambda space is space straight a space scalar