By the end of this topic you will be able to answer this question and other similar problems.

During the topic you will explore the relationships between the sides of right-angled triangles and use the knowledge gained to solve problems involving the sides and angles of right-angled triangles.

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Filed under: 3rd Year | Tagged: trigonometry |

Mr H, on Tuesday 2 September, 2008 at 12:36 said:Wednesday 3 September, Period 5Work in groups to compare sides in right-angled triangles. All start with a 30º-60º-90º triangle, any size.

Note and discuss findings.

Mr H, on Wednesday 3 September, 2008 at 22:38 said:NH’s group were first to discover that the hypotenuse was double the side opposite the 30º angle.

Shared with class and all agreed. Looked at ratios of other sides and discovered similar results.

Mr H, on Wednesday 3 September, 2008 at 22:40 said:Thursday 4 September, Period 4Recap what we discovered yesterday and then look at right triangles with different angles in groups.

Create a table of ratios for angles 5º to 85º from class results. Use the table to calculate lengths and angles.

Mr H, on Thursday 4 September, 2008 at 23:41 said:Class produced superb table of values from scale drawings. All values were within a few thousandths of actual values!

Mr H, on Thursday 4 September, 2008 at 23:41 said:Friday 5 September, Period 5Use trig tables to calculate sides and angles.

Mr H, on Friday 5 September, 2008 at 15:40 said:Done and introduced calculator.

Mr H, on Monday 8 September, 2008 at 22:21 said:Tuesday 9 September, Period 2Worked examples of finding angle and sides.

Trigonometry Problems worksheet, Q1-2.

Mr H, on Tuesday 9 September, 2008 at 13:07 said:Q1 and most of Q2 complete

Mr H, on Tuesday 9 September, 2008 at 13:09 said:Wednesday 10 September, Period 5Space Trig starter questions (height of shuttle and depth of moon crater).

Complete trig worksheet.

Mr H, on Wednesday 10 September, 2008 at 21:23 said:Done but some need further practice to become more confident and fluent.

Mr H, on Wednesday 10 September, 2008 at 21:26 said:Thursday 11 September, Period 4Mixed problems worksheet.

Mr H, on Thursday 11 September, 2008 at 22:09 said:Much better progress today, most of class completed most of (extensive) worksheet.

Mr H, on Thursday 11 September, 2008 at 22:11 said:Friday 12 September, Period 5Return factors homework. Set new homework on trigonometry.

Look at angles of elevation and depression problems.

Go outside to calculate height of school and other objects using trig if weather OK.

If weather poor do Trigonometry – Cooperative Logic Problems activity.

Mr H, on Tuesday 16 September, 2008 at 7:52 said:Weather lovely!

Watched Maths4Real video on Tan Ratio to set scene.

Pupils answered questions while watching and made note of how to calculate the height of an object.

Class then went outside and calculated height of main building to be 9.5m.

Mr H, on Tuesday 16 September, 2008 at 7:53 said:Tuesday 16 September, Period 3Recap what we have learned to date. Worked examples followed by applyibg trig to solve problems.

MiA Ex10.1

Mr H, on Tuesday 16 September, 2008 at 14:30 said:Used ‘show-me’ boards to recap key points then started Ex10.1.

Mr H, on Tuesday 16 September, 2008 at 14:31 said:Wednesday 17 Spetember, Period 5Complete Ex10.1, leave time for Trigonometry – Cooperative Logic Problems activity if possible.

Mr H, on Wednesday 17 September, 2008 at 16:06 said:Non-calculator questions starter & discussion. Looked at a selection of trig problems then worked on Ex10.1.

Did not do coop task as felt needed more time to do proper justice.

Mr H, on Wednesday 17 September, 2008 at 16:07 said:Thursday 18 September, Period 4Continue trig problems, Ex10.3 for first half of period then – Cooperative Logic Problems activity.

Homework due today.

Mr H, on Thursday 18 September, 2008 at 21:17 said:Friday 19 September, Period 5Trig exam questions, model solutions in groups then share with class.

Mr H, on Monday 22 September, 2008 at 22:34 said:Tuesday 23 September, Period 2Review Trig topic, get class to summarise key points then create problems (with ‘stories’) for each group to solve.

Mr H, on Tuesday 23 September, 2008 at 13:14 said:Some very interesting problems created!

Mr H, on Tuesday 23 September, 2008 at 13:16 said:Thursday 25 Septembergroup practical problems using trig:

1. Determine height of cherry trees

2. Check length of 100m running track

3. Calculate total length of playing fields

Will need clipboards, clinometers, tapes.

Mr H, on Thursday 25 September, 2008 at 23:08 said:Good group work. Trees calculated fairly accurately.

100m track very sensitive to angle of depression measured.

Total length of field very difficult to calculate due to very small angle (approx 1 degree)

Good discussion at end on causes of error/difficulty.