Math Is Fun Forum
You are not logged in.
- Topics: Active | Unanswered
Pages: 1
#1 2014-06-06 00:09:12
- David
- Member
- From: Bumpkinland
- Registered: 2014-04-23
- Posts: 3,164
Trigonometric Equations
Hello everyone,
I need help with trigonometric equations, a link to math is fun would be great. But first, could anyone help me with this question? A step-by-step answer would be great. Thanks in advance.
Solve the following trigonometric equations for
(edited)
Last edited by David (2014-06-06 03:56:39)
His dominion is an everlasting dominion, Which shall not pass away, And His kingdom the one Which shall not be destroyed.
Offline
#2 2014-06-06 00:26:05
Re: Trigonometric Equations
First, you've to transform this into an equation of sines. Then, apply the submultiple angle formulae.
I'll do this once I am back from the bookstore.
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#3 2014-06-06 00:29:02
- David
- Member
- From: Bumpkinland
- Registered: 2014-04-23
- Posts: 3,164
Re: Trigonometric Equations
ty
His dominion is an everlasting dominion, Which shall not pass away, And His kingdom the one Which shall not be destroyed.
Offline
#4 2014-06-06 02:35:08
- liuv
- Member
- Registered: 2006-05-14
- Posts: 29
Re: Trigonometric Equations
I'm from Beijing China.
Offline
#5 2014-06-06 02:44:39
Re: Trigonometric Equations
Please post the answer that you originally attached with the first post.
I'm not sure if you want a numerical solution or an exact one.
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#6 2014-06-06 02:53:51
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Trigonometric Equations
The 300° is just an approximation is it not?
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#7 2014-06-06 02:56:08
Re: Trigonometric Equations
How did he get 75 there?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#8 2014-06-06 03:03:55
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Trigonometric Equations
I am not sure, but he should replace the = with ≈ in his work.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#9 2014-06-06 03:54:18
- David
- Member
- From: Bumpkinland
- Registered: 2014-04-23
- Posts: 3,164
Re: Trigonometric Equations
Wait, I will upload a image.
His dominion is an everlasting dominion, Which shall not pass away, And His kingdom the one Which shall not be destroyed.
Offline
#10 2014-06-06 03:55:23
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Trigonometric Equations
Hi;
That says 1 / 2 not 1 / 4.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#11 2014-06-06 03:56:08
- David
- Member
- From: Bumpkinland
- Registered: 2014-04-23
- Posts: 3,164
Re: Trigonometric Equations
oops...
His dominion is an everlasting dominion, Which shall not pass away, And His kingdom the one Which shall not be destroyed.
Offline
#12 2014-06-06 04:00:56
- Bob
- Administrator
- Registered: 2010-06-20
- Posts: 10,621
Re: Trigonometric Equations
using edited version
cos (x/2) = 1/4
Cos2A = 2.cos^2 (A) -1
cos(x) = 2 x (1/4)^2 - 1 = - 7/8
then use acos
Bob
Last edited by Bob (2014-06-06 04:02:02)
Children are not defined by school ...........The Fonz
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you! …………….Bob 
Offline
#13 2014-06-06 04:01:58
Re: Trigonometric Equations
Does using acos give you any exact value?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#14 2014-06-06 04:02:49
- Bob
- Administrator
- Registered: 2010-06-20
- Posts: 10,621
Re: Trigonometric Equations
no. I don't think you can get an exact value easily here.
Bob
Children are not defined by school ...........The Fonz
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you! …………….Bob
Offline
#15 2014-06-06 04:03:59
- David
- Member
- From: Bumpkinland
- Registered: 2014-04-23
- Posts: 3,164
Re: Trigonometric Equations
Could you explain a little bit? ty.
His dominion is an everlasting dominion, Which shall not pass away, And His kingdom the one Which shall not be destroyed.
Offline
#16 2014-06-06 04:08:23
- Bob
- Administrator
- Registered: 2010-06-20
- Posts: 10,621
Re: Trigonometric Equations
sec = 1/cos so invert the equation.
Then use the double angle formula:
The rest is arithmetic.
Bob
Children are not defined by school ...........The Fonz
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you! …………….Bob
Offline
#17 2014-06-06 04:09:34
- David
- Member
- From: Bumpkinland
- Registered: 2014-04-23
- Posts: 3,164
Re: Trigonometric Equations
Thanks Bob and everyone. Is the double angle formula on mif?
His dominion is an everlasting dominion, Which shall not pass away, And His kingdom the one Which shall not be destroyed.
Offline
#18 2014-06-06 04:10:43
Re: Trigonometric Equations
The double angle formula can be derived with the compound angle formula
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#19 2014-06-06 04:14:12
- Bob
- Administrator
- Registered: 2010-06-20
- Posts: 10,621
Re: Trigonometric Equations
Children are not defined by school ...........The Fonz
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you! …………….Bob
Offline
#20 2014-06-06 04:15:19
- Bob
- Administrator
- Registered: 2010-06-20
- Posts: 10,621
Re: Trigonometric Equations
Off-line for a while. I'll be back.
B
Children are not defined by school ...........The Fonz
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you! …………….Bob
Offline
#21 2014-06-06 04:16:56
Re: Trigonometric Equations
These identities are a pain. 
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#22 2014-06-06 19:49:15
- liuv
- Member
- Registered: 2006-05-14
- Posts: 29
Re: Trigonometric Equations
The 300° is just an approximation is it not?
I'm from Beijing China.
Offline
Pages: 1