Scaling the right-angled triangle from the unit circle
I can recognise the right-angled triangle within a unit circle and use proportion to scale to similar triangles.
Scaling the right-angled triangle from the unit circle
I can recognise the right-angled triangle within a unit circle and use proportion to scale to similar triangles.
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Lesson details
Key learning points
- There are specific ratios within the two key right-angled triangles defined by the unit circle.
- The first right-angled triangle has hypotenuse of length one.
- The opposite and adjacent sides of this triangle have lengths sin(θ) and cos(θ), respectively.
- The second right-angled triangle has an adjacent side length of one.
- The opposite side of this triangle has length tan(θ)
Keywords
Trigonometric ratios - The trigonometric ratios are ratios between each pair of lengths in a right-angled triangle.
Opposite - The opposite side of a right-angled triangle is the side which is opposite the marked angle.
Adjacent - The adjacent side of a right-angled triangle is the side which is next to both the right angle and the marked angle.
Common misconception
When reading the values of the trigonometric functions during the explanation slides and the tasks, pupils may think that all the values taken from the graphs are fully accurate.
Explain that many of the values from the trigonometric functions have digits beyond the second decimal place. However, two decimal places is a reasonable degree of accuracy for reading values from the graphs during this lesson.
To help you plan your year 9 maths lesson on: Scaling the right-angled triangle from the unit circle, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your year 9 maths lesson on: Scaling the right-angled triangle from the unit circle, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
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The assessment exit quiz will test your pupils' understanding of the key learning points.
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Explore more key stage 3 maths lessons from the Trigonometry unit, dive into the full secondary maths curriculum, or learn more about lesson planning.
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Lesson video
Prior knowledge starter quiz
6 Questions
Assessment exit quiz
6 Questions
