Year 13 Maths Help Thread

Reply 480

Palette

OP

14

Original post by B_9710

Yeah I would try easier questions first if I were you. Paper 1 2007 seems to be quite easy (relative).

I also heard that the gentlest possible introduction to STEP is STEP I 1994.

Reply 481

Kevin De Bruyne

21

Original post by youreanutter

What resources can i use to revise and selfteach s3

Nothing in particular.. the stats book has it all. They were all I used for all of my modules, including S3 and S4.

Reply 482

Coolsul98

6

Q6. Guys the perimeter part of the question. I dont know how to do it

(edited 7 years ago)

Original post by Coolsul98

Q6. Guys the perimeter part of the question. I dont know how to do it

You can calculate the perimeter using trig, subtraction and the fact that l=r(theta) for an arc of a circle

You can calculate the area with subtraction, for a triangle A = (1/2)ab and the fact that A=(1/2)r^2(theta) for a sector of a circle

(edited 7 years ago)

Reply 484

Zacken

22

Original post by Coolsul98

Q6. Guys the perimeter part of the question. I dont know how to do it

arclegnth is

r\theta

where

\theta

is the angle AOB. Then using trig (sin cos or tan) you can find the length AC once you know OA. Since cos(pi/3) = adjacet/hyp. Then you can find CB andn add all this up to find the perimeter.

got it thanks

OP

Original post by B_9710

Yeah I would try easier questions first if I were you. Paper 1 2007 seems to be quite easy (relative).

I can gladly submit to you STEP I 1994 Q2 and Q7 for marking if you wish :biggrin:

.

Reply 487

Coolsul98

6

Does anyone have any ways on how to approach Vectors?

(edited 7 years ago)

Reply 488

ValerieKR

10

Original post by Coolsul98

Any tips on vectors. finding it really confusing

What sort of tips are you hoping for? What do you find confusing?

Reply 489

Coolsul98

6

As in how to approach it

Original post by Coolsul98

Any tips on vectors. finding it really confusing

Visualising them helped me, but I guess that comes from the fact that I did FP4 where vectors go crazy. It helps to understand where the formulae come from and why they work and when they don't work.

Reply 491

B_9710

18

Original post by Coolsul98

Does anyone have any ways on how to approach Vectors?

Draw a clear diagram and put all the relevant information that you're given on the diagram. It can really help.

Welcome.

Why did they change cos2pi/5 to cos-2pi/5 like im noy sure if to change sintheta to -sin-theta u must use costheta=cos-theta at the same time but if thats not true what is the rrason for changing costheta to a negative im unsure why it was done and if it was neccesary or not
Fp2 complez number question

1472912031035-1992782550.jpg520.9KB

Reply 494

B_9710

18

Original post by youreanutter

Why did they change cos2pi/5 to cos-2pi/5 like im noy sure if to change sintheta to -sin-theta u must use costheta=cos-theta at the same time but if thats not true what is the rrason for changing costheta to a negative im unsure why it was done and if it was neccesary or not
Fp2 complez number question

You want a complex number in the form

r(cos \theta \mathbf{+} i\sin \theta )

.

Reply 495

youreanutter

13

Original post by B_9710

You want a complex number in the form

r(cos \theta \mathbf{+} i\sin \theta )

.

oh thanks i see

Reply 496

jamestg

21

When finding exact values, how can you work out whether something is negative without using a CAST diagram?

An example being on this video at 8:38

Reply 497

B_9710

18

Original post by jamestg

When finding exact values, how can you work out whether something is negative without using a CAST diagram?

An example being on this video at 8:38

You just have to know which trig functions are positive and negative in a given interval. Like you just know that for

0\leq x <\pi /2 ,\ \cos x

is positive and for

\pi /2 < x \leq \pi, \ \cos x

is negative.

Original post by jamestg

When finding exact values, how can you work out whether something is negative without using a CAST diagram?

An example being on this video at 8:38

After getting 90+ UMS in both C3 and C4, this is the first time I ever hear of this quadrant rule lol...

Does it even matter? I can't think of an example where it would as long as you correctly work out sine and cosine of each angle correctly.

The only thing I can think of from your question is that sine is negative for 180-360. And cos is positive for 0-90, 270-360, and negative for 90-270.