Trigonometry Worked Examples: Finding Lengths and Angles — Interactive Lesson (Ages 14–16)

Which ratio do I use? This 19-slide interactive lesson takes students through trigonometry worked examples, choosing the right ratio for finding lengths and angles in right-angled triangles.

Trigonometry Worked Examples for Year 10–11 Maths

Students learn two skills: finding a side length when one length and an angle are given, and finding an angle when two side lengths are known. Worked examples show how to decide between sin and tan, set up the equation and rearrange it, such as x = 20 × sin 70° = 18.8 cm and x = 10 ÷ tan 42° = 11.1 cm. Practice includes a ladder against a wall and triangle problems answered to 3 significant figures.

What’s Included

• 19-slide interactive lesson of trigonometry worked examples
• Learning objectives: find a side length, and find an angle
• Worked examples using sin and tan, with answers to 1 decimal place
• Ladder and triangle problems, with answers to 3 significant figures
• Self-marking questions with instant feedback

Key Benefits for Students

• Shows how to choose the correct ratio for each problem
• Builds confidence rearranging and using a calculator
• Real-context problems such as a ladder against a wall
• Instant feedback on answer questions

Why Teachers Love It

• No prep — ready for whole-class teaching on an interactive whiteboard
• Worked examples model how to set out each calculation
• Self-marking questions support independent practice
• Suits teaching, revision and homework
• A good practice lesson after introducing the three ratios

Love this? You’ll love…

• Pythagoras Theorem — Interactive Lesson (Ages 14–16)
• Trigonometric Ratios Sine Cosine Tangent — Interactive Lesson (KS4)
• Trigonometric Exact Values: Sin, Cos and Tan — Interactive Lesson (Ages 14–16)

A dependable addition to a GCSE trigonometry topic, giving students plenty of worked practice choosing and applying the right ratio. Fluency here is the key to unlocking bearings, 3D problems and the sine and cosine rules.

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FAQ

What year group is this for? Years 10–11 (ages 14–16), GCSE.

Does it cover finding angles? Yes — students find lengths and angles.

Is it self-marking? Yes, with instant feedback on the questions.