Question

K 31. If vector a=21-3j, vector b= 2i+3k,then vector (a+b).(a-b) is *
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Answer 1

Solution



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b×c=∣∣∣∣∣∣∣∣i^22j^−22k^13∣∣∣∣∣∣∣∣=−8i^−4j^+8k^

∣∣∣∣b×c∣∣∣∣=(−8)2+(−4)2+(8)2=12

So, a vector of magnitude 3 and perpendicular to both vector b and c is ∣∣∣∣b×c∣∣∣∣