I was paying attention to the concepts on Trigonometry and it’s interesting to note that the typical short question didn’t appear in Paper 1 instead there were 2.5 questions linked very closely to Trigonometry.

Why Trigonometry you might ask?

Well, many students might not be aware Trigonometry is a fundamental set of formulas and concepts which are closely linked to arc lengths, area of sector, mensuration and any questions involving angles in triangle, area of triangles…

I can’t show you the questions due to copyright but you can get a copy of Ten Years Series book (released in January 2011).

Questions on Trigonometry in 2010 ‘O’ Level E-Maths Paper 2

Question 1 (10 marks) tests candidates on

• TOA CAH SOH (extensively since the diagram consists of 3 right angle triangles). I suspect some might use SIN rule (nothing wrong but more manipulations) instead of TOA CAH SOH to answer the questions
• Understanding of bearings

Question 7 (11 marks) tests candidates on

• Usage of COS rule to find angle
• Ability to ‘see’ and find angle of depression from paper
• Manipulation of area of triangle using formula with ‘sin’

Question 8bii (4 marks) tests candidates on

• Ability to find the height of a triangular surface using TOA CAH SOH

The challenges many students face include:

• Knowing all the formulas but not being able to select the correct approach fast and accurate enough in test and exams.
• Not being able to ‘see’ 3D from paper.
• Lacking the flexibility to manipulate formulas (due to poor Algebraic foundation in Secondary 1 and 2)
• Not learning from repeated mistakes
• Unaware of the misconceptions
• Assumption that you know the important usage of every formula but in fact you don’t

If your child is not scoring ‘A’ for E-Maths, he must know the reason and be prepared to do something about it. In ‘O’ Levels, A1 is unlikely to be 75% and above. It is determined by the bell curve of the entire cohort.

Trigonometry is a very important section in E-Maths and A-Maths. I would like to share with your child the strategies proven to have helped my students to achieve better results in their exams.

Join me in the Dec Trigonometry Workshop today! Click  here to read more.

I am pleased to announce that almost all see an improvement in their Mid Year Results (One boy has his grades jump from F9 to A2! Congrats, B!)

I was reviewing the school a-Math exam papers with one of my students during my A-Math Ultimate Leap Programme when she posted me a good question.

Let’s take a look at her Trigonometry question first:

This was her solution for the question:

There is one misconception in her thoughts, can you spot it?

sin 3x is not equal to sin x + sin 2x!

In fact, the correct formula to choose for this question is

sin 3x = sin (2x + x)

= sin2xcosx + cos2xsinx

Her question was: how do you know which formula to use?

TIP: When the angle involved is ODD, we usually use addition formula (just like in this question).

When angle is EVEN, double angle formula is perhaps the correct one to choose.

Are you confused just like my student, which formula should be use? Leave me a comment.

I hope this post has made your understanding clearer :-)

Below is a list of useful posts on A-Math Trigonometry:

1. How To Prove Trigonometry Identity
2. A-Math Trigo Graphs
3. More A-Math Trigo Graphs
4. Drawing of Trigo Graphs

PS: I will be re-running A-Math Trigonometry Mastery Workshop in July as some students miss out the one in June due to other commitments. Registration is open! Click here for more details