Points and vectors

1003024306

Level: 
A
We are given the points A = [-4;2;3], B = [-5;6;3], D = [1;1;4]. Find the coordinates of a point \( C \), if: \[ \overrightarrow{u} = \overrightarrow{AB}\text{, }\ \overrightarrow{CD} = -\frac12\overrightarrow{u}\]
\( C = \left[\frac12; 3; 4\right] \)
\( C = \left[-\frac12;-3;-4\right] \)
\( C = \left[\frac32;3;4\right] \)
\( C = \left[\frac32;-3;-4\right] \)

1003024307

Level: 
A
Let \( \overrightarrow{a} = (-1;2) \), \( \overrightarrow{b} = (2;1) \), \( \overrightarrow{c} = (-4;3) \). Express vector \( \overrightarrow{c} \) as a linear combination of vectors \( \overrightarrow{a} \) and \( \overrightarrow{b} \).
\( \overrightarrow{c} = 2\overrightarrow{a} - \overrightarrow{b} \)
\( \overrightarrow{c} = 4\overrightarrow{a} - 8\overrightarrow{b} \)
\( \overrightarrow{c} = 4\overrightarrow{a} - \overrightarrow{b} \)
\( \overrightarrow{c} = -2\overrightarrow{a} + \overrightarrow{b} \)

1103020801

Level: 
A
Find the coordinates of the midpoints of the line segments \( AB \), \( BC \), \( AC \). For coordinates of the points \( A \), \( B \) and \( C \), see the picture.
\( S_{AB}=\left[-\frac12;1 \right]\text{, }\ S_{BC}=[4;2 ]\text{, }\ S_{AC}=\left[\frac12; 4\right] \)
\( S_{AB}=\left[-\frac32;2 \right]\text{, }\ S_{BC}=[1;3 ]\text{, }\ S_{AC}=\left[\frac52; 4\right] \)
\( S_{AB}=\left[\frac12;1 \right]\text{, }\ S_{BC}=[4;2 ]\text{, }\ S_{AC}=\left[-\frac12; 4\right] \)
\( S_{AB}=\left[1;-\frac12 \right]\text{, }\ S_{BC}=[2;4 ]\text{, }\ S_{AC}=\left[4;\frac12\right] \)

1103020804

Level: 
A
In the parallelogram \( ABCD \) shown in the picture, \( G \) is the midpoint of \( CD \), \( F \) is the midpoint of \( BC \) and \( \overrightarrow{u}=\overrightarrow{CG} \), \( \overrightarrow{v}=\overrightarrow{CF} \), \( \overrightarrow{a}=\overrightarrow{AD} \) and \( \overrightarrow{b}=\overrightarrow{AC} \). Express vectors \( \overrightarrow{a} \) and \( \overrightarrow{b} \) as a linear combination of vectors \( \overrightarrow{u} \) and \( \overrightarrow{v} \).
\( \overrightarrow{a}=-2\overrightarrow{v};\ \overrightarrow{b}=-2\overrightarrow{u}-2\overrightarrow{v} \)
\( \overrightarrow{a}=\overrightarrow{b}+2\overrightarrow{u};\ \overrightarrow{b}=-2\overrightarrow{u}+2\overrightarrow{v} \)
\( \overrightarrow{a}=\overrightarrow{b}-2\overrightarrow{u};\ \overrightarrow{b}=-\sqrt2\overrightarrow{u}-\sqrt2\overrightarrow{v} \)
\( \overrightarrow{a}=-2\overrightarrow{v};\ \overrightarrow{b}=2\overrightarrow{u}+2\overrightarrow{v} \)

1103020808

Level: 
A
Let \( ABC \) be a triangle. In the picture, the midpoint of the side \( BC \) and the centroid of the triangle are indicated. Out of the following vector relations select the one that is not true.
\( \overrightarrow{ST}= \frac12 \overrightarrow{AT} \)
\( \overrightarrow{AT}= \frac23\overrightarrow{AS} \)
\( \overrightarrow{ST} = -\frac13\overrightarrow{AS} \)
\( \overrightarrow{SA}= -3\overrightarrow{TS} \)