Points and vectors

1003030604

Level: 
B
Let \( \overrightarrow{a}=(2;- 3) \) and \( \overrightarrow{b}=(3;-2) \). Find all the vectors \( \overrightarrow{c} \) such that \[ \overrightarrow{a}\cdot\overrightarrow{c}=8\ \text{ and }\ \overrightarrow{b}\cdot\overrightarrow{c}=27. \]
\( \overrightarrow{c}=(13;6) \)
\( \overrightarrow{c_1}=(13;6);\ \overrightarrow{c_2}=(-13;-6) \)
\( \overrightarrow{c}=(13k;6k);\ k\in\mathbb{R} \)
\( \overrightarrow{c}=(-13;-6) \)

1003030605

Level: 
B
Let \( \overrightarrow{a}=(3;-5) \) and \( \overrightarrow{b}=(6;-10) \). Find all the vectors \( \overrightarrow{c} \) such that \[ \overrightarrow{a}\cdot\overrightarrow{c}=11\ \text{ and }\ \overrightarrow{b}\cdot\overrightarrow{c}=22\text{ .} \]
\( \overrightarrow{c}=(2+5k;-1+3k);\ k\in\mathbb{R} \)
\( \overrightarrow{c}_1=(7;2);\ \overrightarrow{c}_2=(-7;-2) \)
\( \overrightarrow{c}=(2k;-k);\ k\in\mathbb{R} \)
\( \overrightarrow{c}_1=(2;-1);\ \overrightarrow{c}_2=(-2;1) \)

1103021001

Level: 
B
Let \( ABCDEF \) be a regular hexagon with the centre \( S \) and the side of length \( 3\,\mathrm{cm}\). The point \( G \) is the midpoint of the segment \( AB \). The vectors \( \overrightarrow{u} \), \( \overrightarrow{v} \), \( \overrightarrow{w} \), \( \overrightarrow{z} \) are indicated in the hexagon shown in the picture. Find the dot product of: \( \overrightarrow{v}\cdot\overrightarrow{w} \), \( \overrightarrow{v}\cdot\overrightarrow{z} \) and \( \overrightarrow{v}\cdot\overrightarrow{u} \).
\( \overrightarrow{v}\cdot\overrightarrow{w}=9 \), \( \overrightarrow{v}\cdot\overrightarrow{z} = 0 \), \( \overrightarrow{v}\cdot\overrightarrow{u}=27 \)
\( \overrightarrow{v}\cdot\overrightarrow{w}=9 \), \( \overrightarrow{v}\cdot\overrightarrow{z} = 0 \), \( \overrightarrow{v}\cdot\overrightarrow{u}=9\sqrt6 \)
\( \overrightarrow{v}\cdot\overrightarrow{w}=\frac92 \), \( \overrightarrow{v}\cdot\overrightarrow{z} = 0 \), \( \overrightarrow{v}\cdot\overrightarrow{u}=9\sqrt6 \)
\( \overrightarrow{v}\cdot\overrightarrow{w}=\frac92 \), \( \overrightarrow{v}\cdot\overrightarrow{z} = 1 \), \( \overrightarrow{v}\cdot\overrightarrow{u}=27 \)

1103030501

Level: 
B
The vectors \( \overrightarrow{u} \), \( \overrightarrow{v}\), \( \overrightarrow{w} \), \( \overrightarrow{z} \) are indicated in a cube shown in the figure. The cube edge length is \( 1 \). Find the dot products of: \[ \overrightarrow{v}\cdot\overrightarrow{z}\text{ ,}\ \ \overrightarrow{u}\cdot\overrightarrow{v} \text{ ,}\ \ \overrightarrow{w}\cdot\overrightarrow{u}\]
\( \overrightarrow{v}\cdot\overrightarrow{z}=1 \), \( \overrightarrow{u}\cdot\overrightarrow{v}=0 \), \( \overrightarrow{w}\cdot\overrightarrow{u}=1 \)
\( \overrightarrow{v}\cdot\overrightarrow{z}=\frac{\sqrt2}2 \), \( \overrightarrow{u}\cdot\overrightarrow{v}=1 \), \( \overrightarrow{w}\cdot\overrightarrow{u}=\sqrt3 \)
\( \overrightarrow{v}\cdot\overrightarrow{z}=\sqrt2 \), \( \overrightarrow{u}\cdot\overrightarrow{v}=0 \), \( \overrightarrow{w}\cdot\overrightarrow{u}=1 \)
\( \overrightarrow{v}\cdot\overrightarrow{z}=1 \), \( \overrightarrow{u}\cdot\overrightarrow{v}=1 \), \( \overrightarrow{w}\cdot\overrightarrow{u}=\sqrt3 \)

1103030502

Level: 
B
Find the coordinates of the vectors \( \overrightarrow{u} \) and \( \overrightarrow{v} \) given by the picture and evaluate their dot product.
\( \overrightarrow{u}=(-3;6);\ \ \overrightarrow{v} =(-9;-6);\ \ \overrightarrow{u}\cdot\overrightarrow{v} = -9 \)
\( \overrightarrow{u}=(3;-6);\ \ \overrightarrow{v} =(9;6);\ \ \overrightarrow{u}\cdot\overrightarrow{v} = -9 \)
\( \overrightarrow{u}=(-3;6);\ \ \overrightarrow{v} =(-9;-6);\ \ \overrightarrow{u}\cdot\overrightarrow{v} = 9 \)
\( \overrightarrow{u}=(3;-6);\ \ \overrightarrow{v} =(9;6);\ \ \overrightarrow{u}\cdot\overrightarrow{v} = 0 \)

1103030503

Level: 
B
Find the coordinates of the vectors \( \overrightarrow{u} \) and \( \overrightarrow{v} \) given by the picture and evaluate their dot product.
\( \overrightarrow{u}=(-8;-7;9);\ \ \overrightarrow{v} =(8;7;9);\ \ \overrightarrow{u}\cdot\overrightarrow{v} = -32 \)
\( \overrightarrow{u}=(-8;-7;9);\ \ \overrightarrow{v} =(8;7;9);\ \ \overrightarrow{u}\cdot\overrightarrow{v} = 0 \)
\( \overrightarrow{u}=(-8;-7;9);\ \ \overrightarrow{v} =(8;7;9);\ \ \overrightarrow{u}\cdot\overrightarrow{v} = (-64;-49;81) \)
\( \overrightarrow{u}=(8;7;-9);\ \ \overrightarrow{v} =(-8;-7;-9);\ \ \overrightarrow{u}\cdot\overrightarrow{v} = (-64;-49;81) \)

1103030504

Level: 
B
The vectors \( \overrightarrow{u} \) and \( \overrightarrow{v} \) are given by the figure. Find cosine of the angle \(\varphi \) between \( \overrightarrow{u} \) and \( \overrightarrow{v} \). Help: Use the dot product of the given vectors.
\( \cos\varphi=\frac{13\sqrt{10}}{50} \)
\( \cos\varphi=\frac{970}{50} \)
\( \cos\varphi=\frac{3\sqrt{10}}{10} \)
\( \cos\varphi=\frac{\sqrt{10}}{5} \)

1103030505

Level: 
B
The vectors \( \overrightarrow{u} \) and \( \overrightarrow{v} \) are given by the figure. Find cosine of the angle \( \varphi \) between \( \overrightarrow{u} \) and \( \overrightarrow{v} \). Help: Use the dot product of the given vectors.
\( \cos\varphi=-\frac9{17} \)
\( \cos\varphi=\frac9{17} \)
\( \cos\varphi=\frac{\sqrt{17}}{2\sqrt{13}} \)
\( \cos\varphi=-\frac{\sqrt{17}}{2\sqrt{13}} \)

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.
\( \varphi\doteq 104^{\circ} \)
\( \varphi\doteq 76^{\circ} \)
\( \varphi\doteq 100^{\circ} \)
\( \varphi\doteq 80^{\circ} \)