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8th grade Similar shapes: a dilation plus moves worksheet

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Similar shapes: a dilation plus moves

Grade 8 Math Worksheet - Challenge Me

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

  1. Read this first

    Use this

    Coordinate grid, all four quadrants, each square one unit, 20 squares across (−10 to 10), origin in the middle. The design and its copy are both drawn, with D, D′, F and F′ labeled; the middle step is not drawn.

  2. Kira's kite design became a similar copy. D went from (1, 2) to (8, 4), and F from (1, -2) to (8, -4). Which moves did it, in order?

    • a slide 3 units right, then a dilation by 1/2 from the origin
    • a slide 7 units right and 2 units up
    • a dilation by 2 from the origin, then a slide 3 units right
    • a slide 3 units right, then a dilation by 2 from the origin
  3. Luz's rocket design became a similar copy. D went from (2, 4) to (3, 3), and F from (4, -2) to (6, -6). Which moves did it, in order?

    • a slide 2 units down, then a dilation by 3/2 from the origin
    • a dilation by 3/2 from the origin, then a slide 2 units down
    • a slide 2 units down, then a dilation by 2/3 from the origin
    • a slide 1 unit right and 1 unit down
  4. Noah's car design became a similar copy. D went from (4, 2) to (-1, 3), and F from (-2, 4) to (-4, 4). Which moves did it, in order?

    • a dilation by 2 from the origin, then a slide 3 units left and 2 units up
    • a dilation by 1/2 from the origin, then a slide 3 units left and 2 units up
    • a slide 3 units left and 2 units up, then a dilation by 1/2 from the origin
    • a slide 5 units left and 1 unit up
  5. Pia dilated a star sticker by 2 from the origin, then slid it 2 units right and 3 units down. D′ is now at (6, 1). Where did D start? Write it like (7, -3).

  6. Ren slid a snowman sticker 2 units right and 2 units up, then dilated it by 3/2 from the origin. D′ is now at (-3, 6). Where did D start? Write it like (7, -3).

  7. Ari dilates a castle picture from the origin by 2, then dilates the copy by 3/4. One dilation from the origin would do both. What is its scale factor?

  8. Esme dilates a house picture from the origin by 1/2, then dilates the copy by 3. One dilation from the origin would do both. What is its scale factor?

  9. Jun dilates a kite picture by 2 from the origin, then turns it 90° counterclockwise. DF was 5 units and ∠D was 64°. What are D′F′ and ∠D′? Type: length, angle.

  10. Kira dilates a rain umbrella picture by 3/4 from the origin, then flips it across the y-axis. DF was 8 units and ∠D was 110°. What are D′F′ and ∠D′? Type: length, angle.

  11. Luz dilates a sled picture by 5/2 from the origin, then slides it 3 units right. DF was 4 units and ∠D was 35°. What are D′F′ and ∠D′? Type: length, angle.

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8th grade Similar shapes: a dilation plus moves worksheet – printable
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About this worksheet

Similar shapes: a dilation plus moves. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can say that a dilation plus slides, flips and turns makes a similar shape: lengths multiply by k, angles stay the same.
  • I can follow, undo and choose a sequence of moves that takes a shape onto a similar one.
  • I can tell similar from congruent, and check whether two shapes are similar by dividing matching sides.

Standard: 8.G.A.4

Words to know

similar: Same shape, maybe a different size: one is a dilation of the other, moved.

congruent: Same shape and same size.

sequence of moves: Moves done one after another, in a stated order.

matching sides: Sides in the same place on the two shapes.

scale factor from A to B: B's side ÷ A's matching side.

Common mistakes

Your child added the scale factor to a length instead of multiplying.

Your child added the size of the slide to a length, as if sliding stretched the shape. Slide a ruler across the table together: does it get longer?

Your child thought the angles grow with the shape.

What to say

Ask: if a picture is made 3 times as big, is each side 3 longer or 3 times as long?

Ask: when a photo is enlarged, do its corners get any wider?

Questions parents ask

What is the most common mistake with similar shapes: a dilation plus moves?

Your child added the scale factor to a length instead of multiplying.

How can I help my child with similar shapes: a dilation plus moves?

Ask: if a picture is made 3 times as big, is each side 3 longer or 3 times as long?

Are these 8th grade math worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

More grade 8 math

See all grade 8 math

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