Maths

Watch this thread

Announcements

No university offers? Chat with other students about Ucas extra here >>

Find your A-Level exam threads now! >>

start new discussion reply

2 Next

Go to first unread

Skip to page:

galicia

Badges: 5

Rep:

Report Thread starter 4 years ago

Me again, the worried mum.

I need help with four maths questions on behalf of my son. He has been serious ill for the past four months and to help him pass year 4 of school, and not have to repeat the whole year, I seriously need help.

The school have given him a project of 15 maths questions and he can do all but four.

Knowing that cos of A = 1/3 and that 270°<A<360° , calculate sin A and tan (without calculating the value of A).

Thanks

MR1999

Badges: 21

Rep:

Report 4 years ago

(Original post by galicia)
Me again, the worried mum.

I need help with four maths questions on behalf of my son. He has been serious ill for the past four months and to help him pass year 4 of school, and not have to repeat the whole year, I seriously need help.

The school have given him a project of 15 maths questions and he can do all but four.

Knowing that cos of A = 1/3 and that 270°<A<360° , calculate sin A and tan (without calculating the value of A).

Thanks

Use the formulae $\sin A \equiv \sqrt{1-\cos^2 A}$ and $\displaystyle \tan A \equiv \frac{\sin A}{\cos A}$

But since $270 ^{\circ} < A < 360^{\circ} , A$ is in the $\text{IV}$ quadrant, so we need to be careful of the signs of $\sin A$ and $\tan A$ .

Muttley79

Badges: 20

Rep:

Report 4 years ago

(Original post by Desmos)
Use the formulae $\sin A \equiv \sqrt{1-\cos^2 A}$ and $\displaystyle \tan A \equiv \frac{\sin A}{\cos A}$

But since $270 ^{\circ} < A < 360^{\circ} , A$ is in the $\text{IV}$ quadrant, so we need to be careful of the signs of $\sin A$ and $\tan A$ .

If he's in Year4 that is GCSE and so this is not appropriate.

Muttley79

Badges: 20

Rep:

Report 4 years ago

Is this GCSE as you say Year 4? I'd draw a triangle with adjacent side 1 and hypotenuse 3 then you can get sine and tan - then think about CAST.

If he has been ill for so long then repeating the year might be better if he is taking GCSE next year.

thekidwhogames

Badges: 18

Rep:

Report 4 years ago

Use CAST. It's in the fourth quadrant or the C (in CAST) as it's between 270 and 360. Make a triangle to the horizontal and call the acute angle X let's say. We know the adjacent of the triangle is 1 and the hypotenuse 3 (to satisfy CosX = 1/3). Use Pythagoras to get the opposite side to be 2 root 2. In this quadrant, tan = - 2root2 (it's negative) and sine is -2/3 root 2 (negative). Hope this helps.

galicia

Badges: 5

Rep:

Report Thread starter 4 years ago

(Original post by Muttley79)
Is this GCSE as you say Year 4? I'd draw a triangle with adjacent side 1 and hypotenuse 3 then you can get sine and tan - then think about CAST.

If he has been ill for so long then repeating the year might be better if he is taking GCSE next year.

Thanks. But he missed the last 2 months of school and will probably miss the first term if he had to repeat. He has just been diagnosed with Crohns and finally started his treatment yesterday. There is no way the Consultant will let him go to school yet as medication affects his immune system.

It is year 4 but he attends a secondary school here in Galicia NW Spain. He is going to take a year out and then the following school year will start the international baccalaureate.

MR1999

Badges: 21

Rep:

Report 4 years ago

(Original post by Muttley79)
If he's in Year4 that is GCSE and so this is not appropriate.

Clearly he's not in year 4 of British education.

Muttley79

Badges: 20

Rep:

Report 4 years ago

(Original post by Desmos)
Clearly he's not in year 4 of British education.

You've quoted an A level approach for a GCSE question. [year 4 of secondary I assumed]

MR1999

Badges: 21

Rep:

Report 4 years ago

(Original post by Muttley79)
You've quoted an A level approach for a GCSE question. [year 4 of secondary I assumed]

You mentioned CAST which is first taught in C2.

Muttley79

Badges: 20

Rep:

#10

Report 4 years ago

#10

Yes, that's what I assumed.

Muttley79

Badges: 20

Rep:

#11

Report 4 years ago

#11

(Original post by Desmos)
You mentioned CAST which is first taught in C2.

No- it's met at GCSE where I teach,

thekidwhogames

Badges: 18

Rep:

#12

Report 4 years ago

#12

CAST isn't GCSE.

Muttley79

Badges: 20

Rep:

#13

Report 4 years ago

#13

(Original post by thekidwhogames)
CAST isn't GCSE.

It can be ...

thekidwhogames

Badges: 18

Rep:

#14

Report 4 years ago

#14

(Original post by Muttley79)
It can be ...

No, it's not. It is nowhere in the specification and has never been in any exam. The question itself isn't GCSE.

Muttley79

Badges: 20

Rep:

#15

Report 4 years ago

#15

(Original post by thekidwhogames)
No, it's not. It is nowhere in the specification and has never been in any exam. The question itself isn't GCSE.

The OP is not following a UK curriculum so it could be in their GCSE ...

thekidwhogames

Badges: 18

Rep:

#16

Report 4 years ago

#16

(Original post by Muttley79)
The OP is not following a UK curriculum so it could be in their GCSE ...

But then introducing identities (trig) is fine and acceptable. If they're not following the GCSE spec, then both CAST/trig identities should be accepted.

Muttley79

Badges: 20

Rep:

#17

Report 4 years ago

#17

(Original post by thekidwhogames)
But then introducing identities (trig) is fine and acceptable. If they're not following the GCSE spec, then both CAST/trig identities should be accepted.

CAST has been in GCSE and we stil teach it - trig identities have NEVER been in GCSE or O level before that.

thekidwhogames

Badges: 18

Rep:

#18

Report 4 years ago

#18

(Original post by Muttley79)
CAST has been in GCSE and we stil teach it - trig identities have NEVER been in GCSE or O level before that.

GCSE refers to England/Wales in which case CAST has never been taught at GCSE. Also, the trig identities have been introduced in some books of the 9-1 GCSE Maths but it's not part of the spec. Therefore both CAST and trig identities are equally not in the GCSE so giving answers with trig identities I think is fine (not that they're needed).

Muttley79

Badges: 20

Rep:

#19

Report 4 years ago

#19

(Original post by thekidwhogames)
GCSE refers to England/Wales in which case CAST has never been taught at GCSE. Also, the trig identities have been introduced in some books of the 9-1 GCSE Maths but it's not part of the spec. Therefore both CAST and trig identities are equally not in the GCSE so giving answers with trig identities I think is fine (not that they're needed).

GCSE started 30 years ago - CAST has been in the spec - we actually don't know that the OP is doing GCSE it might be iGCSE or similar. Whatever it is, trig identities won't be being taught.

Student1191

Badges: 21

Rep:

#20

Report 4 years ago

#20

Doing that in year 4? Damn

start new discussion

2 Next

Go to first unread

Skip to page:

Quick Reply

Submit reply

Attached files

Replying is easier on our app - Click here to download for FREE!

Write a reply...

new posts

Back
to top

Poll

Join the discussion

Year 12s - where are you at with making decisions about university?

I’ve chosen my course and my university

I’ve chosen my course and shortlisted some universities

I’ve chosen my course, but not any universities

I’ve chosen my university, but not my course

I’ve shortlisted some universities, but not my course

I’m starting to consider my university options

I haven’t started thinking about university yet

I’m not planning on going to university

I’ve chosen my course and my university (7)

43.75%

I’ve chosen my course and shortlisted some universities (4)

25%

I’ve chosen my course, but not any universities (2)

12.5%

I’ve chosen my university, but not my course (0)

I’ve shortlisted some universities, but not my course (0)

I’m starting to consider my university options (2)

12.5%

I haven’t started thinking about university yet (0)

I’m not planning on going to university (1)

6.25%

Latest

My Feed

Oops, nobody has posted
in the last few hours.

Why not re-start the conversation?

Start new discussion

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

Can't find any interesting discussions?

Update your preferences

Quick Reply

Oops, nobody has posted
in the last few hours.

See more of what you like on
The Student Room

Have you seen...?

Poll

Year 12s - where are you at with making decisions about university?

Watched Threads

Oops, nobody has posted
in the last few hours.

See more of what you like on
The Student Room

TSR Support Team

Get Started

Using TSR

Info

TSR Group

Personal statements

Connect with TSR

Maths

Quick Reply

Related discussions

Related articles

Oops, nobody has postedin the last few hours.

Oops, nobody is replying to posts.

See more of what you like onThe Student Room

Have you seen...?

Poll

Year 12s - where are you at with making decisions about university?

Watched Threads

Spotlight

Oops, nobody has postedin the last few hours.

Oops, nobody is replying to posts.

See more of what you like onThe Student Room

TSR Support Team

Get Started

Using TSR

Info

TSR Group

Personal statements

Connect with TSR

Oops, nobody has posted
in the last few hours.

See more of what you like on
The Student Room

Oops, nobody has posted
in the last few hours.

See more of what you like on
The Student Room