Points and Vectors

1103030704

Level: 
A
We are given points \( A = [2;1] \), \( B = [4;-1] \), and \( T = [6;2] \), where point \( T \) is the centroid of triangle \( ABC \). Find the length of the median of triangle \( ABC \) to side \( AC \).
\( |t_b|=\frac{\sqrt{117}}2 \)
\( |t_b|=\frac{\sqrt{45}}2 \)
\( |t_b|=\frac{\sqrt{153}}2 \)
\( |t_b|=\sqrt{117} \)

1103030701

Level: 
A
We are given points \( A = [1;-1;2] \), \( B = [0;5;-3] \), \( S = [2;0;5] \). Point \( S \) is the centre of a parallelogram \( ABCD \). Find the coordinates of vertices \( C \) and \( D \).
\( C = [3;1;8]; D = [4;-5;13] \)
\( C = [4;-5;13]; D = [3;1;8] \)
\( C = [1;1;3]; D = [2;-5;8] \)
\( C = [-3;-1;-8]; D = [-4;5;-13] \)

1003020901

Level: 
C
Let there be vectors: \(\vec{a}=(1;3;-1)\), \(\vec{b}=(0;3;1)\), \(\vec{c}=(-1;2;2)\). Find \(\vec{a}\times\vec{b}\) and \(\left(\vec{a}\times\vec{b}\right)\cdot\vec{c}\).
\(\vec{a}\times\vec{b}=(6;-1;3); \left(\vec{a}\times\vec{b}\right)\cdot\vec{c}=-2\)
\(\vec{a}\times\vec{b}=8; \left(\vec{a}\times\vec{b}\right)\cdot\vec{c}=(-8,16,16)\)
\(\vec{a}\times\vec{b}=(-6;1;-3); \left(\vec{a}\times\vec{b}\right)\cdot\vec{c}=2\)
\(\vec{a}\times\vec{b}=\sqrt{46}; \left(\vec{a}\times\vec{b}\right)\cdot\vec{c}=2\)

9000108807

Level: 
B
Find the angle between the median \(t_{c}\) and side \(c\) in the triangle \(ABC\) for \(A = [1;2]\), \(B = [7;-2]\) and \(C = [6;1]\). Round to the nearest degree. Hint: In geometry, the median \(t_{c}\) of the triangle \(ABC\) is the line segment joining the vertex \(C\) to the midpoint of the opposing side.
\(60^{\circ }\)
\(50^{\circ }\)
\(43^{\circ }\)
\(71^{\circ }\)

9000108808

Level: 
B
Find the angle between the altitude \(v_{c}\) and side \(b\) in the triangle \(ABC\) for \(A = [1;2]\), \(B = [7;-2]\) and \(C = [6;1]\). Round to the nearest degree. Hint: In geometry, the altitude \(v_{c}\) of the triangle \(ABC\) is the line segment through the vertex \(C\) and perpendicular to the line containing the opposite side of the triangle.
\(68^{\circ }\)
\(75^{\circ }\)
\(44^{\circ }\)
\(61^{\circ }\)

9000108706

Level: 
B
Find all vectors which are parallel to the vector \(\vec{u} = (3;-1)\) and have the length equal to \(1\).
\(\left (\frac{3\sqrt{10}} {10} ;-\frac{\sqrt{10}} {10} \right )\), \(\left (-\frac{3\sqrt{10}} {10} ; \frac{\sqrt{10}} {10} \right )\)
\((0;-1)\), \((0;1)\)
\((-3;1)\), \((3;-1)\)
\(\left (\frac{3} {4};-\frac{1} {4}\right )\), \(\left (-\frac{3} {4}; \frac{1} {4}\right )\)