Q:

What is the image of (-9,-3) after a reflection over the line y=-x

Accepted Solution

A:
Answer:(3,9)Step-by-step explanation:The straight line which is perpendicular to the straight line y= -x is given by y=x +c {Since, the product of slopes of two mutually perpendicular straight line is -1} Β Now, if this straight line passes through (-9, -3) point, then -3 =-9 +c, β‡’c =6.Therefore, the straight line which is perpendicular to the line y=-x ....... (1) and passes through (-9,-3) point is y=x+6 ....... (2)Now, solving (1) and (2) we get, 2y =6, β‡’ y=3 and from (1), x=-3Therefore, equations (1) and (2) intersect at (-3, 3) point.If (h,k) is the reflection point of (-9,-3) over the line y =-x, then (-3,3) must be the midpoint of (h,k) and (-9,-3) points.Hence, (h-9)/2 =-3, β‡’h-9 =-6, β‡’h=3and (k-3)/2 =3, β‡’ k-3 = 6, β‡’ k=9Hence, (3,9) is the image point of (-9, -3) after reflection over the line y=-x. (Answer)