Use the image to answer the question. Triangle ABC is reflected across the y -axis to produce triangle DEF . Which segment on DEF is congruent to the segment BC ?

Answer 1

To determine which segment in triangle DEF is congruent to segment BC in triangle ABC after reflecting across the y-axis, we need to analyze how reflection affects the coordinates of the points in the triangle.

When triangle ABC is reflected across the y-axis:

• The x-coordinates of points A, B, and C will change sign, while the y-coordinates remain the same.

For instance, if point B has coordinates (x, y), after reflection across the y-axis, its new coordinates will be (-x, y).

Following this reflection, the segments in triangle DEF will correspond to the original segments in triangle ABC:

• Segment AB will correspond to segment DE.
• Segment AC will correspond to segment DF.
• Segment BC will correspond to segment EF.

As a result, the segment on triangle DEF that is congruent to segment BC from triangle ABC is segment EF.