Eric Nicholas K's answer to idununderstandasinglething's Secondary 4 A Maths Singapore question.

done {{ upvoteCount }} Upvotes
clear {{ downvoteCount * -1 }} Downvotes
Eric Nicholas K
Eric Nicholas K's answer
5997 answers (Tutor Details)
Before you draw each graph, list down these five things.

1. Direction of travel

- Positive sin starts from centre and goes up first
- Negative sin starts from centre and goes down first
- Positive cos starts from top and goes down first
- Negative cos starts from bottom and goes up first

2. Maximum value of function (depending on situation, sin bx or cos bx is to be set to plus 1 or minus 1)

3. Centre value of function

4. Minimum value of function (depending on situation, sin bx or cos bx is to be set to plus 1 or minus 1)

5. Number of cycles in 360 degrees or 2pi, then transform to number of cycles in say 180 degrees if the range they ask you to draw is 180 degrees only

Then we plot the graphs. I plot the graph with higher frequency first because usually it’s more difficult to cramp many cycles in 360 degrees.