## SIMILARITY & TRIGONOMETRY

## OVERVIEW

Trigonometry is introduced as a special case of similarity within right-angled

triangles linking to the introductory lesson in Year 9. Emphasis is placed throughout the steps on linking the trig functions to ratios, rather than just functions. This key topic is introduced early in Year 10 to

allow regular revisiting e.g. when looking at bearings.

## Lesson Resources

Lesson 1 – Enlargement positive scale factors

Lesson 2 – Enlarging from a point

Lesson 3 – Enlargement fractional scale factors

Lesson 4 – Enlargement negative scale factors (Higher only)

Lesson – Similar Shapes

Lesson 5 – Similar Triangles and Parallel Lines

Lesson 6 – Similar Area

Lesson 7 – Similar Volume

Lesson 8 – The Sine Ratio

Lesson 9 – Using all three ratios to find missing lengths

Lesson 10 – Using all three ratios to find missing angles

Lesson 11 – Working with exact values

Lesson 12 – Pythagoras or Trigonometry?

Lesson 13 – Solving area problems

Lesson 14 – Area of non-right angled triangles (Higher only)

Lesson 15 – The Sine Rule (Higher only)

Lesson 16 – The Cosine Rule (Higher only)

Lesson 17 – Sine or Cosine?

Lesson 18 – Bearings and Trigonometry (Higher only)