Matching sides and angles of congruent figures

Answer Key - Grade 8 Math Worksheet - Building Confidence

Circle the best answer, or write your answer on the line.

1. 1.

   Ari slides triangle ABC 8 units left to make A′B′C′ on the grid. Corner A is at (1, 2) and corner B is at (4, 6). How long is side A′B′?

   5
2. 2.

   Bo flips triangle ABC over the y-axis to make A′B′C′ on the grid. Corner A is at (1, 1) and corner B is at (7, 9). How long is side A′B′?

   10
3. 3.

   Esme turns triangle ABC 180° about the origin to make A′B′C′ on the grid. Corner A is at (2, 1) and corner B is at (6, 4). How long is side A′B′?

   5
4. 4.

   Jun flips triangle ABC over the x-axis to make A′B′C′ on the grid. Corner A is at (1, 1) and corner B is at (9, 7). How long is side A′B′?

   10
5. 5.

   Kira flips triangle ABC over the y-axis on the grid to make triangle A′B′C′. Which statement must be true?

   • Triangle A′B′C′ is not congruent to ABC, because a flip turns it backward.
   • Side A′B′ is parallel to side AB.
   • Side A′B′ is as long as side AB, and angle B′ equals angle B.
   • Triangle A′B′C′ is bigger than ABC, because it sits farther from the center.
6. 6.

   Luz turns triangle ABC 90° counterclockwise about the origin on the grid to make triangle A′B′C′. Which statement must be true?

   • Side A′B′ is as long as side AB, and angle B′ equals angle B.
   • Triangle A′B′C′ is bigger than ABC, because it turned around the center.
   • Side A′B′ is parallel to side AB.
   • Triangle A′B′C′ is a mirror image of ABC.
7. 7.

   Noah flips triangle ABC over the x-axis, then slides it 4 units right on the grid to make triangle A′B′C′. Which statement must be true?

   • Triangle A′B′C′ is congruent to ABC: every side and angle matches its partner.
   • Triangle A′B′C′ is not congruent to ABC, because it was flipped over.
   • Triangle A′B′C′ is bigger than ABC, because it ended up farther away.
   • The angles of A′B′C′ are different, because two moves were made.
8. 8.

   Pia knows triangle DFG is congruent to triangle STU, with D↔T, F↔U and G↔S. What is x?

   8
9. 9.

   Tala knows triangle WXY is congruent to triangle GHJ, with W↔H, X↔J and Y↔G. What is x?

   8
10. 10.

    Zee knows triangle BCD is congruent to triangle FGH, with B↔G, C↔H and D↔F. What is x?

    7