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Maths Gcse Edexcel Higher

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  1. Scatter-Graphs-And-Correlation Edexcel Higher
    2 主题
  2. Cumulative-Frequency-And-Box-Plots Edexcel Higher
    4 主题
  3. Histograms Edexcel Higher
    3 主题
  4. Statistical-Diagrams Edexcel Higher
    7 主题
  5. Averages-Ranges-And-Data Edexcel Higher
    8 主题
  6. Combined-And-Conditional-Probability Edexcel Higher
    3 主题
  7. Tree-Diagrams Edexcel Higher
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  8. Simple-Probability-Diagrams Edexcel Higher
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  9. Transformations Edexcel Higher
    5 主题
  10. Vectors Edexcel Higher
    6 主题
  11. 3D-Pythagoras-And-Trigonometry Edexcel Higher
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  12. Sine-Cosine-Rule-And-Area-Of-Triangles Edexcel Higher
    4 主题
  13. Pythagoras-And-Trigonometry Edexcel Higher
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  14. Area-And-Volume-Of-Similar-Shapes Edexcel Higher
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  15. Congruence-Similarity-And-Geometrical-Proof Edexcel Higher
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  16. Volume-And-Surface-Area Edexcel Higher
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  17. Circles-Arcs-And-Sectors Edexcel Higher
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  18. Area-And-Perimeter Edexcel Higher
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  19. Circle-Theorems Edexcel Higher
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  20. Bearings-Scale-Drawing-Constructions-And-Loci Edexcel Higher
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  21. Angles-In-Polygons-And-Parallel-Lines Edexcel Higher
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  22. Symmetry-And-Shapes Edexcel Higher
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  23. Exchange-Rates-And-Best-Buys Edexcel Higher
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  24. Standard-And-Compound-Units Edexcel Higher
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  25. Direct-And-Inverse-Proportion Edexcel Higher
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  26. Problem-Solving-With-Ratios Edexcel Higher
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  27. Ratios Edexcel Higher
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  28. Sequences Edexcel Higher
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  29. Transformations-Of-Graphs Edexcel Higher
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  30. Graphing-Inequalities Edexcel Higher
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  31. Solving-Inequalities Edexcel Higher
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  32. Real-Life-Graphs Edexcel Higher
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  33. Estimating-Gradients-And-Areas-Under-Graphs Edexcel Higher
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  34. Equation-Of-A-Circle Edexcel Higher
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  35. Graphs-Of-Functions Edexcel Higher
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  36. Linear-Graphs Edexcel Higher
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  37. Coordinate-Geometry Edexcel Higher
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  38. Functions Edexcel Higher
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  39. Forming-And-Solving-Equations Edexcel Higher
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  40. Iteration Edexcel Higher
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  41. Simultaneous-Equations Edexcel Higher
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  42. Quadratic-Equations Edexcel Higher
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  43. Linear-Equations Edexcel Higher
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  44. Algebraic-Proof Edexcel Higher
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  45. Rearranging-Formulas Edexcel Higher
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  46. Algebraic-Fractions Edexcel Higher
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  47. Completing-The-Square Edexcel Higher
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  48. Factorising Edexcel Higher
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  49. Expanding-Brackets Edexcel Higher
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  50. Algebraic-Roots-And-Indices Edexcel Higher
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  51. Introduction Edexcel Higher
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  52. Using-A-Calculator Edexcel Higher
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  53. Surds Edexcel Higher
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  54. Rounding-Estimation-And-Bounds Edexcel Higher
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  55. Fractions-Decimals-And-Percentages Edexcel Higher
    3 主题
  56. Simple-And-Compound-Interest-Growth-And-Decay Edexcel Higher
    4 主题
  57. Percentages Edexcel Higher
    3 主题
  58. Fractions Edexcel Higher
    4 主题
  59. Powers-Roots-And-Standard-Form Edexcel Higher
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  60. Prime-Factors-Hcf-And-Lcm Edexcel Higher
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  61. Number-Operations Edexcel Higher
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Exam code:1MA1

Similarity

What are similar shapes?

  • Two shapes are similar if they have the same shape and their corresponding sides are in proportion

    • One shape is an enlargement of the other

How do we prove that two triangles are similar?

  • To show that two triangles are similar you need to show that their angles are the same

    • If the angles are the same then corresponding lengths of a triangle will automatically be in proportion

  • You can use angle properties to identify equal angles

    • Look out for for isosceles triangles, vertically opposite angles and angles on parallel lines

  • If a question asks you to prove two triangles are similar

    • For each pair of corresponding angles

      • State that they are of equal size

      • Give a reason for why they are equal 

How do we prove that two shapes are similar?

  • To show that two non-triangular shapes are similar you need to show that their corresponding sides are in proportion

    • Divide the length of one side by the length of the corresponding side on the other shape to find the scale factor 

  • If the scale factor is the same for all corresponding sides, then the shapes are similar

Examiner Tips and Tricks

  • A pair of similar triangles can often be opposite each other in an hourglass formation.

    • Look out for the vertically opposite, equal angles.

    • It may be helpful to sketch the triangles next to each other and facing in the same direction.

Worked Example

(a) Prove that the two rectangles shown in the diagram below are similar.

Two similar rectangles

 Use the corresponding lengths (15 cm and 6 cm) to find the scale factor

15 over 6 space equals space 2.5

Use the corresponding width (5 cm and 2 cm) to find the scale factor for the other pair of sides

5 over 2 equals 2.5

The two rectangles are similar, with a scale factor of 2.5

(b) In the diagram below, AB and CD are parallel lines.
Show that triangles ABX and CDX are similar.

Two similar triangles

State the equal angles by name, along with clear reasons
Don’t forget to state that similar triangles need to have equal corresponding angles

Angle AXB = angle CXD (vertically opposite angles are equal)
Angle ABC = angle BCD (alternate angles on parallel lines are equal)
Angle BAD = angle ADC (alternate angles on parallel lines are equal)

All three corresponding angles are equal, so the two triangles are similar

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