Question

The point A (a, b) is first reflected in the y-axis and then reflected in the origin to a point A'(- 3, 4). Find the value of a and b.$\left[3Marks\right]$

Answer 1

We know, when any point (x, y) is reflected in y-axis, the sign of the abscissa changes.
$\therefore$ Reflection of point A (a, b) in y-axis is (-a, b).
$\left[1Mark\right]$

Also, we know when any point (x, y) is reflected in the origin, the sign of its abscissa and ordinate both changes.
$\therefore$ Reflection of (-a, b) in origin is A' (a, -b).
$\left[1Mark\right]$

Given A' is (-3, 4).
Hence, on comparing, we get $a=-3$ and $b=-4$.$\left[1Mark\right]$