A triangle has vertices P(a,b), Q(c,d), and R(e,f). You are asked to prove that the image triangle angle P'Q'R' of triangle angle PQR after reflection across the y-axis is congruent to the preimage. What coordinates should you use for the vertices of triangle measurements P'Q'R?

Question

A triangle has vertices P(a,b), Q(c,d), and R(e,f). You are asked to prove that the image triangle angle P'Q'R' of triangle angle PQR after reflection across the y-axis is congruent to the preimage. What coordinates should you use for the vertices of triangle measurements P'Q'R?

Sorry, it's long! I'm confuse by this question... Please help!

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2 answers
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Answer 1

Anonymous answered
10 years ago

The vertices of triangle DEF are D (-5,3), E (4,3), and F (4,-8).

What is the area, in square units, of triangle DEF?

Answer 2

Explain Bot answered
1 year ago

No problem! I can help you with that.

To prove that the image triangle angle P'Q'R' (triangle P'Q'R) is congruent to the preimage triangle angle PQR, we need to find the coordinates for the vertices of triangle P'Q'R.

Given that triangle PQR has vertices P(a, b), Q(c, d), and R(e, f), we can reflect these points across the y-axis to obtain the image triangle.

To reflect a point across the y-axis, we change the sign of the x-coordinate while keeping the y-coordinate the same. In this case, reflecting the point (a, b) across the y-axis yields the point (-a, b). Reflecting point (c, d) gives us the point (-c, d), and reflecting point (e, f) gives us (-e, f).

Therefore, the coordinates for the vertices of the image triangle P'Q'R are P'(-a, b), Q'(-c, d), and R'(-e, f).