C2 Trig question!

Scroll to see replies

you seem to think that 120 and -48.59 are theta

they aren't

In order to use the rules that you want to use you have to use the corresponding value in the first quadrant

BUT

I think you need to consider a different approach to these questions

Too late for a different approach:

Okay so tell me, how would you answer the first question.

x = -48.59.

Which quadrant would you first plot it in? What steps would you take to finding the values?

Reply 21

TenOfThem

I would put -49 in Q4 ... Just as you did

Knowing that I have -ve Sine I would go into Q3 ... Just as you did

I would then read off -49 and -131

Depending on the range

If I wanted +ve values I would use the same red lines that you had and read off 229 and 311

Your problem seems to be that you are trying to use some rules as well as the CAST diagram ... just read from the CAST digram and you have the answers ... the CAST diagram just uses symmetry

(edited 11 years ago)

Reply 22

raheem94

Original post by Kravez

Too late for a different approach:

Okay so tell me, how would you answer the first question.

x = -48.59.

Which quadrant would you first plot it in? What steps would you take to finding the values?

Have you watched the videos that i linked you to?

How is it too late?
There is more than enough time to study a module from scratch and you think that there isn't enough time for learning just a new approach.

It will be better for you to watch some videos about cast to understand it, they will be more helpful.

Reply 23

Kravez

Original post by raheem94

I was away, although I just got back and will watch the videos now. He recommended that I should learn a different method entirely and disregard CAST.

Although my problem was that I was using rules + the CAST diagram as he mentioned in his post above.

Original post by TenOfThem

Your problem seems to be that you are trying to use some rules as well as the CAST diagram ... just read from the CAST digram and you have the answers ... the CAST diagram just uses symmetry

It seems like this was my problem.

(edited 11 years ago)

Reply 24

TenOfThem

Original post by Kravez

He ... he ... his

The little red symbol by my name means ... ... ...

Reply 25

raheem94

Original post by TenOfThem

The little red symbol by my name means ... ... ...

I first thought to tell him, but left it so that he works on maths rather than this.

By the way, i don't think the meaning of the red symbol is very obvious on TSR.

Reply 26

TenOfThem

Original post by raheem94

By the way, i don't think the meaning of the red symbol is very obvious on TSR.

Not to you maybe ... because you never picked which symbol you are ... but he did so he should know :biggrin:

Reply 27

Mr M

Study Forum Helper

Original post by raheem94

By the way, i don't think the meaning of the red symbol is very obvious on TSR.

Really? Do many people think Venus was a man?

Reply 28

TenOfThem

Original post by Mr M

Really? Do many people think Venus was a man?

I expected this to be a comment on the evil that is CAST

:biggrin:

Reply 29

raheem94

Original post by Mr M

Really? Do many people think Venus was a man?

Reply 30

kitriviolet

nono, 40 is anticlockwise from the positive x axis which is the A quadrant.

also, its not that cos x is negative, its cos 3x that is negative. in fact, cos x is positive.

Original post by Kravez

Okay let's say if you were to plot x=40. This would go into the 'C' quadrant but as TenOfThem said it is negative so you can't plot x=40 in the 'C' quadrant as cos can only be positive there. What now?