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by **elizabeth** » Wed Mar 13, 2013 8:39 pm

IB Mathematics HL – Vectors, Scalar Product, perpendicular vectors

How can we find the value of the parameter c for which the vectors $a= \begin{pmatrix} c \\ 2c \\ 4 \end{pmatrix}$ and $b= \begin{pmatrix} 3 \\ -2 \\ 5 \end{pmatrix}$ are perpendicular?

Thanks

by **miranda** » Wed Mar 13, 2013 9:08 pm

IB Mathematics HL – Vectors, dot Product, perpendicular vectors

We know that two vectors are perpendicular if and only their dot product equals zero.

Therefore

$a \cdot b=(c \cdot 3) + (2c \cdot (-2)) + (4 \cdot 5) =3c- 4c+20=0$

$\Rightarrow c= 20$

Hope these help!

by **elizabeth** » Sun Mar 17, 2013 5:11 pm

Thanks miranda!!

ib maths4u | ib maths | ib math | ib mathematics

IB Maths HL Vectors, perpendicular

IB Maths HL Vectors, perpendicular

Re: IB Maths HL Vectors, perpendicular

IB Mathematics HL Vectors, perpendicular