**"Trigonometric equations"**

## GT6 TRIGONOMETRIC IDENTITIES AND EQUATIONS

*By toni On 27 August, 2018 · Leave a Comment*

This workshop reviews reduction formulae in terms of rotations and reflections. It offers learning activities that involve sortingĀ and solving trigonometric equations and finding general solutions, or solutions within a

given domain, using known identities and graphical or unit circle representations. Suggestions are given organising group activies and learners presenting and explaining their ideas […]

## Grades 11 and 12 Always or sometimes

*By toni On 20 May, 2017 · Leave a Comment*

Angles A, B and C are the angles of a triangle. Decide whether each of the following is an identity, always true for all triangles, or an equation, sometimes true. If you decide it is an equation find the solution or solutions and describe the corresponding triangle.

Click here for Notes for Teachers

## Grades 10 to 12 Trig Lengths

*By toni On 23 July, 2016 · Leave a Comment*

In the diagram the line OS is perpendicular to the lines OR and PQ.

The line RS is a tangent at P to the circle centre O and radius 1 unit.

Find the lengths OQ, PQ, PS, OS, OR and RP.

If OS and OR lie on the coordinate axes, what are the coordinates […]

## Grades 11 to 12 – Geometric Trig

*By toni On 21 May, 2012 · 8 Comments*

This is a unit circle with a tangent at A.

The angle marked in the diagram is angle a.

Copy the diagram and find all the angles in terms of the angle a.

Find the six line segments in the diagram corresponding to sina, cosa, tana, 1/sina, 1/cosa and 1/tana.

Find the areas of […]

## Grade 9 and 10 – Making Sixty

*By toni On 18 January, 2012 · Leave a Comment*

Why does this fold create an angle of sixty degrees?

Make a centre crease down the length of the paper then open it up.

Next fold one corner over and onto the centre crease so that the fold line passes through the corner next to it (on the short side of the paper).

You […]

## Grade 9 and 10 – Tet Trouble

*By toni On 18 January, 2012 · Leave a Comment*

Show that is it impossible to have a tetrahedron whose six edges have lengths 10, 20, 30, 40, 50 and 60 units.

Is it possible for a tetrahedron to have edges of lengths 10, 20, 25, 45, 50 and 60 units?

Can you write general rules for someone else to use to check whether […]

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