x Turn on thread page Beta
 You are Here: Home >< Maths

C3 Mixed Exercise 7F Q9 watch

1. Hi,

I was wondering if anybody could help me, I am stuck on C3 Mixed Exercise 7F, Question 9 c and d.

C - solve
sin(θ+40°) + sin(θ+50°) = 0 , 0 ≤ θ ≤ 360°

D - solve
sin² θ/2 = 2sinθ ,0 ≤ θ ≤ 360°

Any help would be appreciated as Physics and Math Tutors Solution jump around and don't really explain anything, which is annoying...

Thanks!
2. (Original post by BenRichi_)
Hi,

I was wondering if anybody could help me, I am stuck on C3 Mixed Exercise 7F, Question 9 c and d.

C - solve
sin(θ+40°) + sin(θ+50°) = 0 , 0 ≤ θ ≤ 360°

D - solve
sin² θ/2 = 2sinθ ,0 ≤ θ ≤ 360°

Any help would be appreciated as Physics and Math Tutors Solution jump around and don't really explain anything, which is annoying...

Thanks!
3. sin(θ) = cos(90-θ)
cos(θ) = sin(90 - θ)
4. (Original post by TeeEm)
Well for C I started by using the addition formulae to expand, but was just left with nothing. And nothing for D
5. sin(x+50) = cos(x+40)
So -tan(x+40) = 0
6. (Original post by NotNotBatman)
sin(θ) = cos(90-θ)
cos(θ) = sin(90 - θ)
Where does this come from?
7. (Original post by BenRichi_)
Well for C I started by using the addition formulae to expand, but was just left with nothing. And nothing for D
does post 3 help?
8. (Original post by TeeEm)
does post 3 help?
Well I understand how I would use it, but don't understand where that is from, I have never seen this before?
9. (Original post by TeeEm)
does post 3 help?
Youre trying too much
10. (Original post by BenRichi_)
Where does this come from?
It's taught in c2. Draw a right angled triangle with an angle marked x, so the other angle will have to be 90-x and you'll see that it works.

or consider the cosine and sine graphs.
11. (Original post by BenRichi_)
Well I understand how I would use it, but don't understand where that is from, I have never seen this before?
standard result taught at C2
12. (Original post by GeologyMaths)
Youre trying too much
I don't think that your solution works, or makes sense...
13. (Original post by BenRichi_)
Well I understand how I would use it, but don't understand where that is from, I have never seen this before?
cos(x) = sin(90-x)
cos(x) = sin90cosx - sinxcos90
cos(x) = cos(x) - 0
14. (Original post by BenRichi_)
Hi,

I was wondering if anybody could help me, I am stuck on C3 Mixed Exercise 7F, Question 9 c and d.

C - solve
sin(θ+40°) + sin(θ+50°) = 0 , 0 ≤ θ ≤ 360°

D - solve
sin² θ/2 = 2sinθ ,0 ≤ θ ≤ 360°

Any help would be appreciated as Physics and Math Tutors Solution jump around and don't really explain anything, which is annoying...

Thanks!
Have u come across the factor formula? if not it is
sinp+ sinq== 2sin(p+q/2)cos(p-q/2).... with p as 40° and q as 50°. Sub in values
and you should come to 2sin(θ+45)=0 and cos(-5)=0 where cos(-5) is invalid therefore solve 2sin(θ+45)=0................... ...ok and tell me what you get
15. (Original post by raman_17)
Have u come across the factor formula? if not it is
sinp+ sinq== 2sin(p+q/2)cos(p-q/2).... with p as 40° and q as 50°. Sub in values
and you should come to 2sin(θ+45)=0 and cos(-5)=0 where cos(-5) is invalid therefore solve 2sin(θ+45)=0................... ...ok and tell me what you get
Thank you very much raman, I was just looking through the C3 book and found this, its the best solution and gives the correct answer!
16. (Original post by BenRichi_)
Thank you very much raman, I was just looking through the C3 book and found this, its the best solution and gives the correct answer!
no worries
17. (Original post by BenRichi_)
Hi,

I was wondering if anybody could help me, I am stuck on C3 Mixed Exercise 7F, Question 9 c and d.

C - solve
sin(θ+40°) + sin(θ+50°) = 0 , 0 ≤ θ ≤ 360°

D - solve
sin² θ/2 = 2sinθ ,0 ≤ θ ≤ 360°

Any help would be appreciated as Physics and Math Tutors Solution jump around and don't really explain anything, which is annoying...

Thanks!
sin(x)=2sin(x/2)cos(x/2)
18. (Original post by BenRichi_)
I don't think that your solution works, or makes sense...
this person has been trolling the maths forum today.
19. (Original post by the bear)
this person has been trolling the maths forum today.
how?

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: January 30, 2016
Today on TSR

Been caught plagiarising...

...for the 2nd time this year

Mum says she'll curse me if I don't go to uni

Discussions on TSR

• Latest
Poll
Useful resources

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

How to use LaTex

Writing equations the easy way

Study habits of A* students

Top tips from students who have already aced their exams

Chat with other maths applicants

Groups associated with this forum:

View associated groups
Discussions on TSR

• Latest

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE
The text passage is a forum post where a student is asking for help with two specific trigonometric equations from a math exercise. The student mentions being stuck on parts C and D of the question and provides the equations. Other users have responded with hints and suggestions for solving the problems.
single_question
- the post contains a single mathematical question with two parts (c and d), but no answer is provided in the text.
Given a text passage, determine:
    1. If it contains a mathematical question (including word problems or calculations)
    2. If an answer to that mathematical question is provided in the text

First, describe the content structure you found in 1-2 sentences.

Then provide your analysis in the following format:
TYPE: <one of the following values>
- NO_QUESTION
- SINGLE_QUESTION
- SINGLE_QUESTION_WITH_ANSWER
- MULTIPLE_QUESTIONS
- MULTIPLE_QUESTIONS_WITH_ANSWERS
system
x Turn on thread page Beta
 You are Here: Home >< Maths

C3 Mixed Exercise 7F Q9 watch

1. Hi,

I was wondering if anybody could help me, I am stuck on C3 Mixed Exercise 7F, Question 9 c and d.

C - solve
sin(θ+40°) + sin(θ+50°) = 0 , 0 ≤ θ ≤ 360°

D - solve
sin² θ/2 = 2sinθ ,0 ≤ θ ≤ 360°

Any help would be appreciated as Physics and Math Tutors Solution jump around and don't really explain anything, which is annoying...

Thanks!
2. (Original post by BenRichi_)
Hi,

I was wondering if anybody could help me, I am stuck on C3 Mixed Exercise 7F, Question 9 c and d.

C - solve
sin(θ+40°) + sin(θ+50°) = 0 , 0 ≤ θ ≤ 360°

D - solve
sin² θ/2 = 2sinθ ,0 ≤ θ ≤ 360°

Any help would be appreciated as Physics and Math Tutors Solution jump around and don't really explain anything, which is annoying...

Thanks!
3. sin(θ) = cos(90-θ)
cos(θ) = sin(90 - θ)
4. (Original post by TeeEm)
Well for C I started by using the addition formulae to expand, but was just left with nothing. And nothing for D
5. sin(x+50) = cos(x+40)
So -tan(x+40) = 0
6. (Original post by NotNotBatman)
sin(θ) = cos(90-θ)
cos(θ) = sin(90 - θ)
Where does this come from?
7. (Original post by BenRichi_)
Well for C I started by using the addition formulae to expand, but was just left with nothing. And nothing for D
does post 3 help?
8. (Original post by TeeEm)
does post 3 help?
Well I understand how I would use it, but don't understand where that is from, I have never seen this before?
9. (Original post by TeeEm)
does post 3 help?
Youre trying too much
10. (Original post by BenRichi_)
Where does this come from?
It's taught in c2. Draw a right angled triangle with an angle marked x, so the other angle will have to be 90-x and you'll see that it works.

or consider the cosine and sine graphs.
11. (Original post by BenRichi_)
Well I understand how I would use it, but don't understand where that is from, I have never seen this before?
standard result taught at C2
12. (Original post by GeologyMaths)
Youre trying too much
I don't think that your solution works, or makes sense...
13. (Original post by BenRichi_)
Well I understand how I would use it, but don't understand where that is from, I have never seen this before?
cos(x) = sin(90-x)
cos(x) = sin90cosx - sinxcos90
cos(x) = cos(x) - 0
14. (Original post by BenRichi_)
Hi,

I was wondering if anybody could help me, I am stuck on C3 Mixed Exercise 7F, Question 9 c and d.

C - solve
sin(θ+40°) + sin(θ+50°) = 0 , 0 ≤ θ ≤ 360°

D - solve
sin² θ/2 = 2sinθ ,0 ≤ θ ≤ 360°

Any help would be appreciated as Physics and Math Tutors Solution jump around and don't really explain anything, which is annoying...

Thanks!
Have u come across the factor formula? if not it is
sinp+ sinq== 2sin(p+q/2)cos(p-q/2).... with p as 40° and q as 50°. Sub in values
and you should come to 2sin(θ+45)=0 and cos(-5)=0 where cos(-5) is invalid therefore solve 2sin(θ+45)=0................... ...ok and tell me what you get
15. (Original post by raman_17)
Have u come across the factor formula? if not it is
sinp+ sinq== 2sin(p+q/2)cos(p-q/2).... with p as 40° and q as 50°. Sub in values
and you should come to 2sin(θ+45)=0 and cos(-5)=0 where cos(-5) is invalid therefore solve 2sin(θ+45)=0................... ...ok and tell me what you get
Thank you very much raman, I was just looking through the C3 book and found this, its the best solution and gives the correct answer!
16. (Original post by BenRichi_)
Thank you very much raman, I was just looking through the C3 book and found this, its the best solution and gives the correct answer!
no worries
17. (Original post by BenRichi_)
Hi,

I was wondering if anybody could help me, I am stuck on C3 Mixed Exercise 7F, Question 9 c and d.

C - solve
sin(θ+40°) + sin(θ+50°) = 0 , 0 ≤ θ ≤ 360°

D - solve
sin² θ/2 = 2sinθ ,0 ≤ θ ≤ 360°

Any help would be appreciated as Physics and Math Tutors Solution jump around and don't really explain anything, which is annoying...

Thanks!
sin(x)=2sin(x/2)cos(x/2)
18. (Original post by BenRichi_)
I don't think that your solution works, or makes sense...
this person has been trolling the maths forum today.
19. (Original post by the bear)
this person has been trolling the maths forum today.
how?

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: January 30, 2016
Today on TSR

Been caught plagiarising...

...for the 2nd time this year

Mum says she'll curse me if I don't go to uni

Discussions on TSR

• Latest
Poll
Useful resources

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

How to use LaTex

Writing equations the easy way

Study habits of A* students

Top tips from students who have already aced their exams

Chat with other maths applicants

Groups associated with this forum:

View associated groups
Discussions on TSR

• Latest

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE
user
The text passage is a forum post where a student is asking for help with two specific trigonometric equations from a math exercise. The student mentions being stuck on parts C and D of the question and provides the equations. Other users have responded with hints and suggestions for solving the problems.

TYPE: SINGLE_QUESTION
- The post contains a single mathematical question with two parts (C and D), but no answer is provided in the text.