## [Video]E-Math: Speed-time Graph to Distance-time & Acceleration-time Graph

I was asked the above question in this comment. I understand many students are facing the challenge in sketching distance-time graph given speed-time and vice versa. I have prepared 2 videos to share with you what I taught my students in my weekly coaching programme.

Video 1: Convert Speed-time graph to Distance-time graph.
(10 min)

Video 2: Convert Speed-time graph to Acceleration-time graph.(3min)

(I'm sorry there's an error in the video at time 2:10s, the acceleration should be -6)

## Should I Drop A-Math (Additional Mathematics)?

Some of the common questions I get around this period (before registration of GCE 'O' level exams) is that 'Should I Drop A-Math?', 'Can I still study H2 Math in JC if I didn't take A-Math at O level?'

This post is also suitable for Secondary two students who will be choosing their subject combination at the end of the year.

'Should I Drop A-Math?'

This question usually pops out after a long period of unsuccessful attempts to pass A-Math or when it was recommended by teachers to drop the subject.

I have a poem to share: To Drop Or To Perserve On, Read the “Don’t Quit” Poem (Click to read)

'Can I still study H2 Math in JC if I didn't take A-Math at O level?'

I have also answered this question previously in this post: What happens if I do not take A-Maths?

Just a note : I have recently communicated with Temasek Junior College (TJC) Math teacher. For students intending to study H1 Math (Art Stream), 'O' level A-Math is not a requirement.

## O Level A-Math Trigonometry Basics : How Do We Know Which Formula To Use?

For the past month, other than being busy with the June Intensive Revision Programmes, I was also packed with Mid Year Exam Papers Review for my group of students.

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.