Combined Transformation
Find the coordinates of the image of a point A(3, -5) after reflection on the line x + y = 0 followed by the rotation through +90° about the origin.
A(3, -5) A'(5, -3)
Again, A" be the final image when point A' is rotated through +90° about the origin,
A'(5, -3) A"(3, 5)
Find the coordinates of the image of a point (4, 7) when it is first rotated about the origin through -90° and then the image so formed is translated by
A(4, 7) A'(7, -4)
Again, A" be the final image when point A' is translated by
,
A'(7, -4) A"(7 + 3, -4 + 4) = A"(10, 0)
The point P(2, -3) is reflected on the X-axis. The image P" thus obtained is rotated through +90° about origin. Find the co-ordinates of the final image P" and P'.
P(2, -3) P'(2, 3)
Again, P" be the final image when point P' is rotated through +90°
about origin,
P'(2, 3) P"(-3, 2)
Reflect the point P(3, 4) on the y-axis. Rotate the image so obtained about the origin and through 90° in positive direction about the origin and find its final image.
P(3, 4) P'(-3, 4)
Again, P" be the final image when point P' is rotated through 90°
in the positive direction.
P'(-3, 4) P"(-4, -3)
Point P(-2,3) is first reflected on y-axis and the image so obtained is rotated through -90° about the origin. Find the coordinate of the image formed after the rotation.
P(-2, 3) P'(2, 3)
Again, P" be the final image after rotating P' through -90° about
the origin.
P'(2, 3) P"(3, -2)
Point A(2, 5) is first reflected on X-axis. The image so obtained is rotated through 90° in positive direction about origin. Find the final image of A(2,5).
A(2, 5) A'(2, -5)
Again, A" be the final image when point A' is rotated through 90°
in positive direction about origin.
A'(2, -5) A"(5, 2)
If r1 is the reflection on y-axis and r2 is the reflection on the line y - 5 = 0, then find the image of point (5, 3) under the combined transformation r1∘r2.
r2 is the reflection on y - 5 = 0, so,
A(x, y) A'(x, 10 - y)
r1 is the reflection on y-axis. so,
A'(x, 10 - y) A"(-x, 10 - y)
Finally,
A(x, y) A"(-x, 10 - y)
P" be the final image of point P(5, 3) under the given combination,
then,
P(5, 3) P"(-5, 7)
Reflect point P(5, 6) on the line x = 2. Enlarge the image so obtained by E[(0,0), 2]. Write the coordinates of the image.
P(5, 6) P'(2 × 2 - 5, 6), P'(-1, 6)
Also, P" be the final image obtained when P' is enlarged by E[(0,0) ,2],
P'(-1, 6) P"(-1 × 2, 6
× 2), P"(-2, 12)
Hence, the coordinate of the images are P'(-1, 6) and P"(-2, 12).
Reflect point A(4, 5) on the line y = 2. Enlarge the image so obtained by E[(0,0),2]. Write the coordinate of the image.
A(4, 5) A'(4, 4 - 5), A'(4, -1)
Also, A" be the final image obtained by enlargement of A' on E[(0, 0), 2],
A'(4, -1) A"(8, -2)
If r1 is the reflection about the X-axis and r2 is the rotation about +90° through the origin, find the image of the point A(3, -6) under the combined transformation of r1∘r2.
r2 is the rotation about +90° through origin, so,
A(x, y) A'(-y, x)
r1 is the reflection on x-axis. so,
A'(-y, x) A"(-y, -x)
Finally,
A(x, y) A"(-y, -x)
P" be the final image of point P(3, -6) under the given combination,
then,
P(3, -6) P"(6, -3)
T denotes a translation vector and R denotes the reflection in the line y = 3. If R∘T (a, 3) = (5, b), find the values of a and b.
T denotes a translation vector , so,
T(a, 3) T'(a + 2, 6)
From above,
R∘T(a , 3) = R(a + 2, 6)
R denotes the reflection
in the line y = 3. so,
R(a + 2, 6) R'(a + 2, 0)
So, R∘T(a , 3) = (a + 2, 0)
Hence, by comparing it with (i), we get, a = 3 and b = 0.
Point (4, -3) is reflected in the line x = 0 at first and then the image so formed is reflected in the line y = k so that the final image (-4, 9) is obtained. Find the value of k.
A(4, -3) A'(-4, -3)
Also, A" be the final image formed by reflecting A' in the line y = k.
so,
A'(-4, -3) A"(-4, 2k + 3)
We have given, A"(-4, 9)
Comparing the coordinates of A", we get, 2k + 3 = 9, so, k = 3.
If r1 represents the reflection about x-axis and r2 represents the rotation about the origin through +90°, find the image point of the point N(-3, 2) under the combined transformation of r1∘r2.
r2 is the rotation about +90° through origin, so,
A(x, y) A'(-y, x)
r1 is the reflection on x-axis. so,
A'(-y, x) A"(-y, -x)
Finally,
A(x, y) A"(-y, -x)
P" be the final image of point P(-3, 2) under the given combination,
then,
P(-3, 2) P"(-2, 3)
R1 and R2 denote the reflection in the line y = 2 and line x = -y respectively. Which point has the image A'(-3, 2) under the combined transformation R1∘R2? Find it.
R2 is the reflection in the line x = -y, so,
P(x, y) P'(-y, -x)
R1 is the reflection in the line y = 2. so,
P'(-y, -x) P"(-y, 4 + x)
Finally,
P(x, y) P"(-y, -x) --- (I)
Let the point A(a, b) has the image A'(-3, 2) under the given
combination, then,
A(a, b) A'(-3, 2) --- (II)
Comparing the value of a and b by the help of (I) and (II), we get, a = -2 and b = 3
Hence, the required point A(a, b) is A(-2, 3).Find the co-ordinates of the point A whose image after reflection about the line y = x, followed by the reflection about the line y = 0 is A"(6, -5).
A(x, y) A'(y, x)
Again, A" be the image formed when A' is reflected about the line y = 0.
A'(y, x) A"(y, -x)
So, from above,
A(x, y) A"(y, -x)
We have given, A"(6, -5). So, comparing A"(y, -x) and A"(6, -5), we get,
x = 5 and y = 6.