InterviewSolution
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InterviewSolution
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If the points A(1, 2), B(2, 4) and C(3, a) are collinear, what is the length BC ?A. `sqrt(2)` unitB. `sqrt(3)` unitC. `sqrt(5)` unitD. 5 unit |
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Answer» Correct Answer - C Since the points are collinear. `|(1,2,1),(2,4,1),(3,a,1)|=0` Expanding the determinant `implies 1|(4,1),(a,1)|-2|(2,1),(3,1)|+1|(2,4),(3,a)|=0` `implies (4-a)-2(2-3)+1(2a-12)=0` `implies 4-a+2+2a-12=0` `implies a-6=0` `implies a=6` Thus, Coordinates of C are (3, 6). Thus, `BC=sqrt((3-2)^(2)+(6-4)^(2))` `=sqrt(1+4)=sqrt(5)` unit |
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