Advertisements
Advertisements
Question
Point A (1 , -5) is mapped as A' on rflection in the line y = 1. The point B (-5 , 1) is mapped as B' on reflection in the line y = 4. Write the co-ordinaes of A' and B' . Calculate AB'.
Solution
A (1 , -5) , he co-ordinate of A' = (1 , 2 × 1 - (- 5)) = (1 , 7)
B (-5 , 1) , the co-ordinate of B' = (-5 , 2 × 4 - (1)) = (-5 , 7)
The distance AB' = `sqrt ((-5-1)^2 + (7 - (-5))^2)`
=`sqrt ((-6)^2 + 12^2)`
= `sqrt (36 + 144)`
= `sqrt 180`
= 13.41 units
APPEARS IN
RELATED QUESTIONS
A point P is its own image under the reflection in a line l. Describe the position of point the P with respect to the line l.
State the co-ordinates of the following point under reflection in x-axis:
(3, 2)
State the co-ordinates of the following point under reflection in the line x = 0:
(–6, 4)
S' is the image of S under reflection in the origin. If the co-ordinates of S are (2,-5), write the co-ordinates of S'.
Find the co-ordinates of the image of A (-5, 4) after reflection in the line
y = 4
State the co-ordinates of the following point under reflection in x-axis:
(–5, 4)
State the co-ordinates of the following point under reflection in x-axis:
(0, 0)
Point A (5, 1) on reflection on X- axis is mapped as A’. Also A on reflection on Y- axis is mapped as A”.
(i) Write the co-ordinates of A’.
(ii) Write the co-ordinates of A”.
(iii) Calculate the distance A’ A”.
(iv) On which coordinate axis does the middle point M of A” A’ lie?
Use a graph paper to answer the following questions. (Take 1 cm = 1 unit on both axis):
(i) Plot A (4, 4), B (4, – 6) and C (8, 0), the vertices of a triangle ABC.
(ii) Reflect ABC on the y-axis and name it as A’B’C’.
(iii) Write the coordinates of the images A’, B’ and C’.
(iv) Give a geometrical name for the figure AA’ C’B’ BC.
(v) Identify the line of symmetry of AA’ C’ B’ BC.
