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BAC1 tech · Mathematics
Vectors and geometry · Vectors

Movements in the plane

A drone that changes position, a piece in a video game that is reflected in a mirror, an antenna that shifts because of interference: these are all transformations of the plane. Each one is described by a precise vector operation, and all of them preserve distances: the shape that moves is not distorted.

Before you start, make sure you know: Midpoint of a line segment (4th ESO)
Before you start, make sure you know: Parallel and perpendicular lines (4th ESO)

Translation

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A delivery drone is at position $P(3, -2)$, expressed in kilometres relative to its base. The controller sends it an instruction to make a straight-line displacement…

A delivery drone is at position $P(3, -2)$, expressed in kilometres relative to its base. The controller sends it an instruction to make a straight-line displacement defined by the translation vector $\vec{v} = (-5, 4)$. Determine the coordinates of the drone's new position.

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A laser cutting machine moves in a straight line on a metal sheet from the initial point $A(-1, 5)$ to the final point $B(4, 2)$. Calculate the translation vector that…

A laser cutting machine moves in a straight line on a metal sheet from the initial point $A(-1, 5)$ to the final point $B(4, 2)$. Calculate the translation vector that describes this movement exactly.

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The trajectory of a conveyor belt follows the line with equation $y = 2x - 1$. Due to space requirements in the factory, the entire belt is translated $3$ units to the…

The trajectory of a conveyor belt follows the line with equation $y = 2x - 1$. Due to space requirements in the factory, the entire belt is translated $3$ units to the left and $2$ units upwards. Write the general equation of the new line that defines the translated trajectory.

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Point reflection (central symmetry) about a point

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In the design of a symmetrical garden, a fountain is to be placed at point $F'$, which is the reflection of a statue located at $E(4, 7)$ with respect to a central post…

In the design of a symmetrical garden, a fountain is to be placed at point $F'$, which is the reflection of a statue located at $E(4, 7)$ with respect to a central post located at the origin $O(0, 0)$. Find the coordinates where the fountain should be installed.

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Two communications satellites, $S_1$ and $S_2$, orbit symmetrically with respect to a central space station. If $S_1$ is at position $(8, -3)$ and the space station is…

Two communications satellites, $S_1$ and $S_2$, orbit symmetrically with respect to a central space station. If $S_1$ is at position $(8, -3)$ and the space station is at $(2, 1)$, calculate the coordinates of the position of satellite $S_2$.

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An architect designs a bridge whose arch has a critical anchoring point at $A(-3, 5)$. To maintain visual symmetry in a 3D rendering with respect to the water surface,…

An architect designs a bridge whose arch has a critical anchoring point at $A(-3, 5)$. To maintain visual symmetry in a 3D rendering with respect to the water surface, which coincides with the x-axis ($y=0$), they need to locate the virtual reflection of this point under the water. Determine the coordinates of this symmetrical point.

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Reflection in a line

Geometric construction of the image of a point P under reflection in a line r, using the foot of the perpendicular M as the midpoint. P M P' r
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In a graphic design program, a polygon with a key vertex at point $V(5, -2)$ has been drawn. An axial symmetry (reflection) across the angle bisector of the first and…

In a graphic design program, a polygon with a key vertex at point $V(5, -2)$ has been drawn. An axial symmetry (reflection) across the angle bisector of the first and third quadrants (line $y=x$) is applied. Analytically determine the coordinates of the reflected vertex $V'$.

X Y y=x V V' = ?
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A laser beam is emitted from a projector situated at point $P(-2, 4)$. In front of it, there is a plane mirror placed exactly along the line with equation…

A laser beam is emitted from a projector situated at point $P(-2, 4)$. In front of it, there is a plane mirror placed exactly along the line with equation $r \equiv x - 2y + 5 = 0$. Calculate the coordinates of the virtual point $P'$ (the reflection of $P$ across the mirror) from which the reflected light appears to originate.

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Two villages, $A(1, 5)$ and $B(7, 2)$, need to connect to a main water pipe running in a straight line along the x-axis ($y=0$). A pumping station $P$ is to be built on…

Two villages, $A(1, 5)$ and $B(7, 2)$, need to connect to a main water pipe running in a straight line along the x-axis ($y=0$). A pumping station $P$ is to be built on the main pipe such that the total length of the secondary pipes ($AP + PB$) is minimised. Using the concept of reflection, calculate the exact coordinates of point $P$ and the minimum total length of the pipe.

X (Pipeline) Y A B A' P
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Transformations applied to equations of shapes

Translation of a circle in the plane, where the radius stays constant and only the position of the centre changes. original centre translated centre
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A mobile phone mast provides coverage in a circular area whose Cartesian equation is $x^2 + y^2 - 4x + 6y - 12 = 0$. Due to interference issues with a nearby building,…

A mobile phone mast provides coverage in a circular area whose Cartesian equation is $x^2 + y^2 - 4x + 6y - 12 = 0$. Due to interference issues with a nearby building, the company decides to translate the mast (the centre of the circle) according to the vector $\vec{v} = (-3, 5)$. Determine the general equation of the new coverage area.

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An agricultural plot is in the shape of a triangle with vertices at $A(0, 0)$, $B(4, 0)$ and $C(2, 5)$. The local council compulsory purchases the plot and, in exchange,…

An agricultural plot is in the shape of a triangle with vertices at $A(0, 0)$, $B(4, 0)$ and $C(2, 5)$. The local council compulsory purchases the plot and, in exchange, gives the owner another plot obtained by applying a reflection across the vertical line $x = 6$ to the original triangle. Calculate the vertices of the new plot and prove analytically that the area of the plot has not changed.

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Composition of transformations

Diagram of the composition of transformations showing that applying a translation and a reflection in opposite orders gives different final points. A translation → reflection reflection → translation same point?
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In a video game animation, the geometric centre of a character located at $A(1, 3)$ undergoes a translation by vector $\vec{t} = (4, -2)$ followed immediately by a point…

In a video game animation, the geometric centre of a character located at $A(1, 3)$ undergoes a translation by vector $\vec{t} = (4, -2)$ followed immediately by a point symmetry (point reflection) with respect to point $C(2, 0)$. Find the final position of the character and verify analytically whether the result would be the same by applying the point symmetry first and then the translation.

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An isometry in the plane transforms the point $A(1, 2)$ into $A'(5, 4)$ and the point $B(3, -1)$ into $B'(7, 1)$. a) Show that the distance between $A$ and $B$ is the…

An isometry in the plane transforms the point $A(1, 2)$ into $A'(5, 4)$ and the point $B(3, -1)$ into $B'(7, 1)$.

  1. a) Show that the distance between $A$ and $B$ is the same as that between $A'$ and $B'$.
  2. b) Determine whether the described transformation corresponds to a pure translation or a point reflection, justifying your answer analytically and finding the corresponding translation vector or centre of symmetry.
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Summary

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