Trigonometry: Sine, Cosine and Tangent — Interactive Lesson (Ages 14–16)

Where do sin, cos and tan actually come from? This 27-slide interactive lesson introduces sine, cosine and tangent from the ground up, starting with the sides of a right-angled triangle.

Introducing Sine, Cosine and Tangent in Year 10–11 Maths

Students begin with what trigonometry is: calculations involving the sides and angles of a right-angled triangle. They label the hypotenuse, opposite and adjacent sides with drag-and-drop activities, learn the ratios sin θ, cos θ and tan θ as ratios of the sides, and see why the ratios stay the same for a given angle. They also learn to put their calculator in degree mode and use the inverse function to find an angle.

What’s Included

• 27-slide interactive lesson introducing trigonometry
• The hypotenuse, opposite and adjacent sides, with drag-and-drop labelling
• Definitions of sine, cosine and tangent as ratios of sides
• Calculator guidance, including degree mode and inverse functions
• Quiz, fill-in-the-blank and sorting activities with instant feedback

Key Benefits for Students

• Builds a clear understanding of what the ratios mean
• Reinforces side labelling before calculating
• Teaches the calculator skills that lose the most marks
• Instant feedback on answer questions

Why Teachers Love It

• No prep — ready for whole-class teaching on an interactive whiteboard
• Varied activities keep students engaged
• Self-marking questions support independent practice
• Suits teaching, revision and homework
• A natural first lesson before worked examples

Love this? You’ll love…

• Pythagoras Theorem — Interactive Lesson (Ages 14–16)
• Trigonometry Finding Lengths And Angles — 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 a secure introduction before they move on to finding lengths and angles. Clear side labelling and calculator habits here prevent many common errors later.

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FAQ

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

Does it cover finding angles? Yes — it introduces the inverse function for finding an angle.

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