1.

`|a-b|` किसके तुल्ये हैA. `2sqrt2`B. `2sqrt10`C. 5D. 10

Answer» Correct Answer - B
दिया है `|a|=7,|b|=11`
तथा `|a+b|=10sqrt3`
अब `|a-b|^(2)=|a|^(2)+|b|^(2)-2a.b...(i)`
`therefore |a+b|=10sqrt3`
`therefore |a+b|^(2)=100xx3`
`Rightarrow (7)^(2)+(11)^(2)+2a.ab=30`
`Rightarrow 49+121+2a.b=300`
`Rightarrow 2a.b.=300-170 Rightarrow 2a.b.=130`
अब, |a|, |b| तथा 2a.b के मान सभी में रखने पर
`|a-b|^(2)=(7)^(2)+(11)^(2)-130`
`=49+121-130`
`=170-130=40`
`therefore |a-b|=sqrt40=2sqrt10`


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