Points and vectors

1103030601

Level: 
B
In the cube \( ABCDEFGH \) find the angle \( \varphi \) between the vectors \( \overrightarrow{b}=\overrightarrow{EB} \) and \( \overrightarrow{a}=\overrightarrow{AK} \), where \( K \) is the midpoint of \( HG \). Round \( \varphi \) to the nearest degree. Help: Choose the appropriate coordinate system.
\( \varphi\doteq 104^{\circ} \)
\( \varphi\doteq 76^{\circ} \)
\( \varphi\doteq 100^{\circ} \)
\( \varphi\doteq 80^{\circ} \)

1103024310

Level: 
A
The picture shows the triangle \( KLM \) with indicated vectors \( \overrightarrow{a} \), \( \overrightarrow{b} \), \( \overrightarrow{c} \) in a coordinate system. What are the vector coordinates \( \overrightarrow{b} \)? Express \( \overrightarrow{b} \) as a linear combination of \( \overrightarrow{a} \) and \( \overrightarrow{c} \).
\( \overrightarrow{b} = \left(1;3;4.5\right);\ \overrightarrow{b} = \frac12\overrightarrow{a} + \frac12\overrightarrow{c} \)
\( \overrightarrow{b} = \left(3;1;4.5\right);\ \overrightarrow{b} = \overrightarrow{a} + \overrightarrow{c} \)
\( \overrightarrow{b} = \left(1;3;4.5\right);\ \overrightarrow{b} = \overrightarrow{a} + \overrightarrow{c} \)
\( \overrightarrow{b} = \left(3;1;4.5\right);\ \overrightarrow{b} = \frac12\overrightarrow{a} + \frac12\overrightarrow{c} \)

1103024309

Level: 
A
Given the vectors \( \overrightarrow{a} \), \( \overrightarrow{b} \), \( \overrightarrow{c} \) shown in the picture, express a vector \( \overrightarrow{b} \) as a linear combination of vectors \( \overrightarrow{a} \) and \( \overrightarrow{c} \).
\( \overrightarrow{b} = 2\overrightarrow{a} + \overrightarrow{c} \)
\( \overrightarrow{b} = 2\overrightarrow{a} - \overrightarrow{c} \)
\( \overrightarrow{b} = -2\overrightarrow{a} + \overrightarrow{c} \)
\( \overrightarrow{b} = -2\overrightarrow{a} - \overrightarrow{c} \)

1103024308

Level: 
A
Given the vectors \( \overrightarrow{a} \), \( \overrightarrow{b} \), and \( \overrightarrow{c} \) shown in the picture, express the vector \( \overrightarrow{c} \) as a linear combination of vectors \( \overrightarrow{a} \) and \( \overrightarrow{b} \).
\( \overrightarrow{c} = -2\overrightarrow{a} + \overrightarrow{b} \)
\( \overrightarrow{c} = -\overrightarrow{a} + \frac12\overrightarrow{b} \)
\( \overrightarrow{c} = -\frac32\overrightarrow{a} + \overrightarrow{b} \)
\( \overrightarrow{c} = -2\overrightarrow{a} + \frac32\overrightarrow{b} \)

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 \( \overrightarrow{b} \).
\( \overrightarrow{c} = 2\overrightarrow{a} - \overrightarrow{b} \)
\( \overrightarrow{c} = 4\overrightarrow{a} - 8\overrightarrow{b} \)
\( \overrightarrow{c} = 4\overrightarrow{a} - \overrightarrow{b} \)
\( \overrightarrow{c} = -2\overrightarrow{a} + \overrightarrow{b} \)

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: \[ \overrightarrow{u} = \overrightarrow{AB}\text{, }\ \overrightarrow{CD} = -\frac12\overrightarrow{u}\]
\( C = \left[\frac12; 3; 4\right] \)
\( C = \left[-\frac12;-3;-4\right] \)
\( C = \left[\frac32;3;4\right] \)
\( C = \left[\frac32;-3;-4\right] \)

1103024305

Level: 
A
In a tetrahedron \( ABCD \), let \( \overrightarrow{b} = \overrightarrow{AB} \), \( \overrightarrow{c} = \overrightarrow{AC} \), \( \overrightarrow{d} = \overrightarrow{AD} \), \( \overrightarrow{e} = \overrightarrow{AE} \) and \( \overrightarrow{f} = \overrightarrow{DE} \). Further let \( E \) be the midpoint of \( BC \). Express vectors \( \overrightarrow{e} \) and \( \overrightarrow{f} \) as a linear combination of vectors \( \overrightarrow{b} \), \( \overrightarrow{c} \), \( \overrightarrow{d} \).
\( \overrightarrow{e} = \frac12\overrightarrow{b} + \frac12\overrightarrow{c};\ \overrightarrow{f} = \frac12\overrightarrow{b} + \frac12\overrightarrow{c} - \overrightarrow{d} \)
\( \overrightarrow{e} = \frac12\overrightarrow{b} + \frac12\overrightarrow{d};\ \overrightarrow{f} = \overrightarrow{b} + \overrightarrow{c} + \overrightarrow{d} \)
\( \overrightarrow{e} = \overrightarrow{b} + \overrightarrow{c};\ \overrightarrow{f} =\frac12\overrightarrow{b} + \frac12\overrightarrow{c} - \overrightarrow{d} \)
\( \overrightarrow{e} = \frac12\overrightarrow{b} + \frac12\overrightarrow{c};\ \overrightarrow{f} = \frac12\overrightarrow{b} + \frac12\overrightarrow{c} + \overrightarrow{d} \)

1103024304

Level: 
A
The picture shows a rectangular cuboid \( ABCDEFGH \). In the cuboid find the vector that is the sum of \( \overrightarrow{BC} + \overrightarrow{AE} + \overrightarrow{CF} + \overrightarrow{FA} + \overrightarrow{HG} \).
\( \overrightarrow{BF} \)
\( \overrightarrow{BE} \)
\( \overrightarrow{BG} \)
\( \overrightarrow{BH} \)

1103024303

Level: 
A
The picture shows a rectangular cuboid \( ABCDEFGH \) with \( \overrightarrow{a} = \overrightarrow{AB} \), \( \overrightarrow{b} = \overrightarrow{AD} \), \( \overrightarrow{c} = \overrightarrow{AE} \), \( \overrightarrow{x} = \overrightarrow{AK} \) and \( \overrightarrow{y} = \overrightarrow{AL} \). Point \( K \) is the midpoint of \( FG \) and point \( L \) is the centre of face \( BCGF \). Express vectors \( \overrightarrow{x} \) and \( \overrightarrow{y} \) as a linear combination of vectors \( \overrightarrow{a} \), \( \overrightarrow{b} \), \( \overrightarrow{c} \).
\( \overrightarrow{x} = \overrightarrow{a} + \frac12\overrightarrow{b} + \overrightarrow{c};\ \overrightarrow{y} = \overrightarrow{a} + \frac12\overrightarrow{b} + \frac12\overrightarrow{c} \)
\( \overrightarrow{x} = \frac12\overrightarrow{a} + \overrightarrow{b} + \frac12\overrightarrow{c};\ \overrightarrow{y} = \overrightarrow{a} - \frac12\overrightarrow{b} + \frac12\overrightarrow{c} \)
\( \overrightarrow{x} = \overrightarrow{a} + \frac12\overrightarrow{b} + \frac12\overrightarrow{c};\ \overrightarrow{y} = \overrightarrow{a} - \frac12\overrightarrow{b} + \frac12\overrightarrow{c} \)
\( \overrightarrow{x} = \overrightarrow{a} + \frac12\overrightarrow{b} + \frac12\overrightarrow{c};\ \overrightarrow{y} = \frac12\overrightarrow{a} + \frac12\overrightarrow{b} + \frac12\overrightarrow{c} \)