Question

The vertices of Upper DeltaABC are Upper A left parenthesis negative 2 comma 5 right parenthesis​, Upper B left parenthesis negative 2 comma 3 right parenthesis​, and Upper C left parenthesis negative 5 comma 2 right parenthesis. If Upper DeltaABC is reflected across the​ y-axis to produce the image Upper Delta​A'B'C', find the coordinate of the vertex Upper B​'.

Answer 1

When a point is reflected across the y-axis, the x-coordinate is negated.

So, the coordinate of the vertex B' will be the negation of the x-coordinate of B:

B' = (-(-2), 3) = (2, 3)

Therefore, the coordinate of the vertex B' is (2, 3).