Similarity

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. In △ABC\triangle ABC, a line parallel to BCBC meets ABAB at DD and ACAC at EE, with AD=5AD = 5, DB=3DB = 3 and AE=9AE = 9. Find ECEC.Not to scale
  11. In a triangle, BC=26BC = 26. The segment joining the midpoints of ABAB and ACAC has length…
  12. DE∥BCDE \parallel BC with DD on ABAB, EE on ACAC; AD=2AD = 2, DB=7DB = 7, AE=3AE = 3. Find ACAC.Not to scale