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यदि ` ( veca + vecb) . ( veca - vecb)=8` और ` | veca| = 8 |vecb|` हो तो ` | veca|` एवं ` | vecb|` ज्ञात कीजिए । |
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Answer» दिया है , `( veca + vecb) .( veca - vecb ) = 8` ` implies veca "." veca - veca "." vecb + vecb "." veca - vecb "." vecb =8` `implies | veca|^(2) -|vecb}|^(2) =8` `implies (8 |vecb| )^(2) -|vecb|^(2)=8` `implies |vecb|=sqrt((8)/(63))=(2)/(3)sqrt((2)/(7))` तथा ` | veca| = 8 | vecb|=8 ((2)/(3)sqrt((2)/(7)))=(16)/(3) sqrt((2)/(7))` |
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