Question

Point A (1,-5) is mapped as A' on reflection in the line y= l . The point B (-5, 1) is mapped as B' on reflection in the line y=4. Write the co-ordinates of A' and B'. Calculate AB'. 

Answer 1

A(l ,-5), the co-ordinates of A'= (1, 2x1-(-5)) = (1, 7) 

B (-5, 1), the co-ordinatesof B' = (-5, 2x4-(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