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# please can anyone help me with vectors? watch

1. can someone help me with ii? I can't find D.

BD vector equation is r=(-1,7,11)+ lambda (3, -4,0)
2. (Original post by 0utdoorz)

can someone help me with ii? I can't find D.

BD vector equation is r=(-1,7,11)+ lambda (3, -4,0)
Let's find . Given that the position vector of D is (-1,7,11)+ lambda (3, -4,0) (where lambda is a particular constant), this means that the position vector is B-D. The magnitude of B-D is 15, this implies that the square of each vector component of B-D = 15^2 = 225. This should give you a quadratic equation in lambda.

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Updated: May 17, 2013
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