Mathematics
The triangle ABC where A(1, 2), B(4, 8), C(6, 8) is reflected in the x-axis to triangle A'B'C'. The triangle A'B'C' is then reflected in the origin to the triangle A''B''C''. Write down the coordinates of A'', B'', C''. Write down a single transformation that maps ABC onto A''B''C''.
Answer
We know that,
Rule to find reflection of a point in x-axis :
- Retain the abscissa i.e. x-coordinate.
- Change the sign of ordinate i.e. y-coordinate.
∴ Coordinates of
⇒ A(1, 2) on reflection in x-axis becomes A'(1, -2).
⇒ B(4, 8) on reflection in x-axis becomes B'(4, -8).
⇒ C(6, 8) on reflection in x-axis becomes C'(6, -8).
We know that,
Rules to find the reflection of a point in the origin :
- Change the sign of abscissa i.e. x-coordinate.
- Change the sign of ordinate i.e. y-coordinate.
∴ Coordinates of
⇒ A'(1, -2) on reflection in origin becomes A''(-1, 2).
⇒ B'(4, -8) on reflection in origin becomes B''(-4, 8).
⇒ C'(6, -8) on reflection in origin becomes C''(-6, 8).
A single transformation that maps A ⇒ A'', B ⇒ B'' and C ⇒ C'' is reflection in y-axis.
Hence, the coordinates of A'', B'' and C'' are (-1, 2), (-4, 8) and (-6, 8) respectively, and a single transformation that maps ABC to A''B''C'' is reflection in y-axis.
Related Questions
Given two points P and Q, and that (1) the image of P on reflection in y-axis is the point Q and (2) the mid point of PQ is invariant on reflection in x-axis. Locate (i) the x-axis (ii) the y-axis and (iii) the origin.
The image of a point P on reflection in a line l is a point P'. Describe the location of the line l.
The points (6, 2), (3, -1) and (-2, 4) are the vertices of a right angled triangle. Check whether it remains a right angled triangle after reflection in the y-axis.
Plot the points A(2, -3), B(-1, 2) and C(0, -2) on the graph paper. Draw the triangle formed by reflecting these points in the x-axis. Are the two triangles congruent ?