Symmetries in space
A laser beam bounces off a flat mirror, an object is reflected in a video game, a mechanical part has to be symmetric about an axis: in all three cases you are asking about the same kind of point, the image (the symmetric point). And in all three cases you calculate it with the same tool as always, the midpoint, changing only what you reflect in: a point, a plane or a line.
Symmetry about a point
In video game design software, an object located at point $P(4, -2, 6)$ must be reflected with respect to a control point (centre of symmetry) located at $M(1, 3, 2)$.…
In video game design software, an object located at point $P(4, -2, 6)$ must be reflected with respect to a control point (centre of symmetry) located at $M(1, 3, 2)$. Calculate the coordinates of the symmetric point $P'$ where the reflected object will appear.
It is known that the point $A'(0, 8, -4)$ is the symmetric point of $A(2, -2, 6)$ with respect to a centre of symmetry $C$. Determine the coordinates of this centre $C$…
It is known that the point $A'(0, 8, -4)$ is the symmetric point of $A(2, -2, 6)$ with respect to a centre of symmetry $C$. Determine the coordinates of this centre $C$ using the midpoint relationship.
Symmetry about a plane
Calculate the symmetric point of $Q(3, -5, 7)$ with respect to the coordinate plane $XY$. Hint: Remember that the equation of the plane $XY$ is $z = 0$.
Calculate the symmetric point of $Q(3, -5, 7)$ with respect to the coordinate plane $XY$.
Hint: Remember that the equation of the plane $XY$ is $z = 0$.
Given the point $P(1, 0, 1)$, find its symmetric point with respect to the plane $\pi: x + y + z = 5$ by following these steps: 1. Find the line $r$ perpendicular to…
Given the point $P(1, 0, 1)$, find its symmetric point with respect to the plane $\pi: x + y + z = 5$ by following these steps:
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Find the line $r$ perpendicular to $\pi$ passing through $P$.
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Calculate the point of intersection $M$ between the line $r$ and the plane $\pi$ (foot of the perpendicular).
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Use $M$ as the midpoint to find the symmetric point $P'$.
Calculate the coordinates of the point $Q$, which is the symmetric point of the point $P(1, 0, 5)$ with respect to the plane with equation $\pi: 2x + y - z - 3 = 0$.…
Calculate the coordinates of the point $Q$, which is the symmetric point of the point $P(1, 0, 5)$ with respect to the plane with equation $\pi: 2x + y - z - 3 = 0$. Briefly explain the steps followed (obtaining the perpendicular line, intersection point and midpoint).
Symmetry about a line
Find the point symmetric to $P(1, 2, 3)$ with respect to the line $r$ that coincides with the $OX$-axis.
Find the point symmetric to $P(1, 2, 3)$ with respect to the line $r$ that coincides with the $OX$-axis.
Calculate the symmetric point of $B(5, 5, 5)$ with respect to the line $s$ given by: $$s: \begin{cases} x = 1 \\ y = 2 \\ z = \lambda \end{cases}$$ Note: This is a…
Calculate the symmetric point of $B(5, 5, 5)$ with respect to the line $s$ given by:
$$s: \begin{cases} x = 1 \\ y = 2 \\ z = \lambda \end{cases}$$Note: This is a vertical line, parallel to the $OZ$ axis, that passes through the point $(1, 2, 0)$.
The figure shows the view from above (the $XY$ plane): the line $s$, being vertical, looks like a point, and the projection of $B$ is also shown.
Given the line $r$ defined by the parametric equations: $r: \begin{cases} x = 1 + 2\lambda \\ y = \lambda \\ z = -1 + \lambda \end{cases}$ Find the point symmetric to…
Given the line $r$ defined by the parametric equations:
$r: \begin{cases} x = 1 + 2\lambda \\ y = \lambda \\ z = -1 + \lambda \end{cases}$
Find the point symmetric to $A(3, 2, 1)$ with respect to that line.
Symmetries of whole lines and planes
A laser beam is projected following the path of the line $r: \frac{x-1}{2} = \frac{y+1}{-1} = \frac{z}{1}$. The ray strikes a polished metal surface located in the plane…
A laser beam is projected following the path of the line $r: \frac{x-1}{2} = \frac{y+1}{-1} = \frac{z}{1}$. The ray strikes a polished metal surface located in the plane $XY$ (plane $z=0$). Calculate the equation of the line $s$ containing the reflected ray.
Note: The reflected line is the reflection of the incident line with respect to the plane of incidence.
Consider the points $A(1, 1, 1)$ and $B(3, 5, 5)$. Find the equation of the plane $\pi$ acting as a "plane of symmetry" between both points (that is, the plane with…
Consider the points $A(1, 1, 1)$ and $B(3, 5, 5)$. Find the equation of the plane $\pi$ acting as a "plane of symmetry" between both points (that is, the plane with respect to which $A$ and $B$ are symmetric).