Dilations, similarity and slope

Practice sheet

Fresh questions from the whole chapter, to do on paper.

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  1. Dilate A(3,1)A(3, 1) about the origin with scale factor 2. Tap its image.
  2. A dilation takes a segment of length 3 to a segment of length 11. Find the scale factor.
  3. A triangle is dilated with scale factor 5. What happens to its angles?
    1. They stay the same
    2. They are multiplied by 5
    3. They grow by 5 degrees
  4. Two polygons are similar. A side of length 5 corresponds to a side of length 15. Another side of the small polygon has length 9. Find the matching side of the large one.
  5. A polygon has perimeter 20. It is enlarged by a scale factor of 5. Find the new perimeter.
  6. A shape has area 9. It is enlarged by a scale factor of 2. Find the new area.
  7. Two triangles each have a 76∘76^\circ angle and a 50∘50^\circ angle. What can you conclude?
    1. They are similar (AA)
    2. They are congruent
    3. Nothing without side lengths
  8. △ABC∼△DEF\triangle ABC \sim \triangle DEF with AB=8AB = 8, BC=7BC = 7 and DE=25DE = 25. Find EFEF.Not to scale
  9. Which figures are always similar to each other?
    1. Any two squares (for example sides 7 and 14)
    2. Any two rectangles
    3. Any two isosceles triangles
  10. Find the slope of the line through (6,2)(6, 2) and (9,8)(9, 8).
  11. Find the slope of the line through (6,5)(6, 5) and (8,0)(8, 0).
  12. A slope triangle on a line has a horizontal side of 6 and a vertical side of 2. Another slope triangle on the same line has a horizontal side of 24. How long is its vertical side?