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Grade 11Mechanics

sir i have a question in vector chapter that if vector a+b vector is equal to R vector and vector a+2b vector is perpendicular to vector a then find the value of b

Profile image of Shivam Prakash
8 Years agoGrade 11
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1 Answer

Profile image of Arun
8 Years ago

Here we are given two lines a+ 2b and a which are inclined at 90 degrees.

Thus applying dot product on these lines,

a× (a+2b)=0

a^2+2ab=0

a^2=-2ab

a=-2b

Now a+b=r

-2b+b=r

Thus b+r=0. Or b=-r