Math Help Forum - Trigonometry http://www.mathhelpforum.com/math-help/ Graphing trig expressions, identities, angles, applied questions en Thu, 09 Sep 2010 07:10:47 GMT vBulletin 60 http://www.mathhelpforum.com/math-help/images/misc/rss.png Math Help Forum - Trigonometry http://www.mathhelpforum.com/math-help/ Trigonometry Proof http://www.mathhelpforum.com/math-help/f14/trigonometry-proof-155601.html Wed, 08 Sep 2010 23:33:47 GMT Can someone please prove this equation: _ Cos x _ + _ Cos x _ = 2Sec x 1 - Sin x 1 + Sin x Can someone please prove this equation:

Cos x + Cos x = 2Sec x
1 - Sin x 1 + Sin x ]]> Trigonometry GAVREED2 http://www.mathhelpforum.com/math-help/f14/trigonometry-proof-155601.html Rotation of a square on a plane http://www.mathhelpforum.com/math-help/f14/rotation-square-plane-155548.html Wed, 08 Sep 2010 12:25:23 GMT Hi All, I hope you can help (and I hope this is the right forum for this subject) I have a resizeable plane (say 300 x 300 in size) On this plane I have a square (say 290 x 290 in size) When i rotate this square on this plane by say 25 degrees around the squares center parts of the square... Hi All,

I hope you can help (and I hope this is the right forum for this subject)

I have a resizeable plane (say 300 x 300 in size)
On this plane I have a square (say 290 x 290 in size)

When i rotate this square on this plane by say 25 degrees around the squares center parts of the square are no longer visible on the existing plane.

My goal is to have the plane resize based on the new square but all I have available is the original dimensions of the plane, the original dimensions of the square and the angle it's being rotated by in my problem i do have access to various trigonometric functions such as cos and sin, I also know the center of the original square.

basically i'm looking for an equation which would take the angle and dimensions of the original square and plane and produce the new correct dimensions for the plane so that it engulfs the new square

Please anyone that could help I am desperate for help

kind regards
James ]]> Trigonometry hellzone http://www.mathhelpforum.com/math-help/f14/rotation-square-plane-155548.html Find SEC http://www.mathhelpforum.com/math-help/f14/find-sec-155524.html Wed, 08 Sep 2010 05:29:36 GMT Find SEC Can someone tell me if this is correct Given that sec(theta) = 1.75. find (theta) in degrees Image: http://www.mathhelpforum.com/math-help/vlatex/pics/63_2dc4699cc3349d7ad82484c603d890c8.png Find SEC
Can someone tell me if this is correct

Given that sec(theta) = 1.75. find (theta) in degrees



]]> Trigonometry GAVREED2 http://www.mathhelpforum.com/math-help/f14/find-sec-155524.html sin(A+B) and cos rule http://www.mathhelpforum.com/math-help/f14/sin-b-cos-rule-155519.html Wed, 08 Sep 2010 04:15:54 GMT Solving using sin(A+B) and cos rule Can someone show each od the steps and answer for this question. It will give something to work off for the rest of them. Very much appreciated *1) Using the identities for sin(A+B) and cos^2(theta)+sin^2(theta)=1.* *Find sine 65 degrees, given that sin... Solving using sin(A+B) and cos rule
Can someone show each od the steps and answer for this question. It will give something to work off for the rest of them. Very much appreciated

1) Using the identities for sin(A+B) and cos^2(theta)+sin^2(theta)=1.

Find sine 65 degrees, given that sin 40(degrees)=0.643 and sin 25(degrees)=0.423?
]]> Trigonometry GAVREED2 http://www.mathhelpforum.com/math-help/f14/sin-b-cos-rule-155519.html Proof that this equation is valid (have tried to solve myself many times..) http://www.mathhelpforum.com/math-help/f14/proof-equation-valid-have-tried-solve-myself-many-times-155475.html Tue, 07 Sep 2010 17:06:32 GMT First of all, I must say that I really like this board. Mathematics is my favorite subject in school and I find many things I read here very informative..

My question:
I've been trying to proof the following equation to be true for 2 days now, but I just don't seem to get it right. Could you guys help me with it? (You don't even have to show the full way how you did it, some info on how I should get started would be perfect too).

]]> Trigonometry DaFlyinFin http://www.mathhelpforum.com/math-help/f14/proof-equation-valid-have-tried-solve-myself-many-times-155475.html Solution of Oblique Triangles Help http://www.mathhelpforum.com/math-help/f14/solution-oblique-triangles-help-155467.html Tue, 07 Sep 2010 14:44:11 GMT One diagonal of a parallelogram is 16.5. It makes angle of 36°10' and 14°30' respectively with the sides. Find the sides.]]> How to solve for this problem?

> One diagonal of a parallelogram is 16.5. It makes angle of 36°10' and 14°30' respectively with the sides. Find the sides. ]]> Trigonometry khms http://www.mathhelpforum.com/math-help/f14/solution-oblique-triangles-help-155467.html Using Trigonometric Identity http://www.mathhelpforum.com/math-help/f14/using-trigonometric-identity-155431.html Tue, 07 Sep 2010 06:08:19 GMT a) Find the exact value of sin 135 by using sin (180 – 45)

b) Find the exact value of sin 225 by using sin (270 – 45)
b) Use the value of sin 225 found in b to find sin (–15) by using sin (225 – 240) ]]> Trigonometry soni http://www.mathhelpforum.com/math-help/f14/using-trigonometric-identity-155431.html Sin and Cos http://www.mathhelpforum.com/math-help/f14/sin-cos-155404.html Tue, 07 Sep 2010 01:24:45 GMT How do I solve this? I have been working on this same problem for about an hour and can't come up with anything. I have to find the value of A, w, and b.

2sin(12x + 1) + 3sin(12x + 3) = A sin(wx + b)

Any help (with steps included) would be GREATLY appreciated! Thanks! ]]> Trigonometry aeagan2 http://www.mathhelpforum.com/math-help/f14/sin-cos-155404.html Trigonometry and Surds http://www.mathhelpforum.com/math-help/f14/trigonometry-surds-155371.html Mon, 06 Sep 2010 19:12:48 GMT Hello there,

I have a problem solving question which has been frustrating me:

A triangle has sides of lengths √6, 3√2 and 3√3 units.

Is the triangle right angled? You must give a reason for your answer.

Any help would be greatly appreciated, thank you.

OJW ]]> Trigonometry OJW http://www.mathhelpforum.com/math-help/f14/trigonometry-surds-155371.html <![CDATA[What's the difference between these two trig identity problems?]]> http://www.mathhelpforum.com/math-help/f14/whats-difference-between-these-two-trig-identity-problems-155336.html Mon, 06 Sep 2010 12:00:17 GMT 1) 2 \tan x=3 \sin x 2 \frac{\sin x}{\cos x}=3 \sin x \rightarrow 2 \sin x = 3 \sin x \cos x \rightarrow \sin x(2 - 3 \cos x)=0 a) \sin x = 0 \rightarrow x =180n b) \cos x = \frac{2}{3} \rightarrow x =48.19 + *360n* 2) 2 \sin 2x \cos ^2 x = \sin 2x \sin 2x(2 \cos ^2 x -1) =0 \rightarrow a)... 1)

a)
b) 48.19 + 360n

2)

a)
b)
45 + 360n

of course the answer to number 2 is 45 + 180n
but the answer to number 1 is 48.19 + 360n! So what's the difference between the two? They are both cosine functions. I just thought always add 360 degrees because that's when the angle repeats itself.

(*fixed the bold...) ]]> Trigonometry jayshizwiz http://www.mathhelpforum.com/math-help/f14/whats-difference-between-these-two-trig-identity-problems-155336.html bearing http://www.mathhelpforum.com/math-help/f14/bearing-155335.html Mon, 06 Sep 2010 11:31:21 GMT Attachment 18840

kindly answer the bearing... i got the angle at forest island but i dont know how to get the bearing in from forst island to home port..

the bearing should be South East, but what degrees
Attached Images
 
]]> Trigonometry aeroflix http://www.mathhelpforum.com/math-help/f14/bearing-155335.html sin(x), sin(2x), sin(1/2)....what is the period? http://www.mathhelpforum.com/math-help/f14/sin-x-sin-2x-sin-1-2-what-period-155316.html Mon, 06 Sep 2010 07:23:38 GMT sin(x), sin(2x), sin(1/2)....what are the periods? Pls explain to me the concepts involved so I can remember more clearly. Thanks. sin(x), sin(2x), sin(1/2)....what are the periods?

Pls explain to me the concepts involved so I can remember more clearly.

Thanks. ]]> Trigonometry stupidguy http://www.mathhelpforum.com/math-help/f14/sin-x-sin-2x-sin-1-2-what-period-155316.html Help with simple goniometrics http://www.mathhelpforum.com/math-help/f14/help-simple-goniometrics-155228.html Sun, 05 Sep 2010 09:05:59 GMT Hi heres my problem -

tan(α/2) = (l/2)/d, hence
α = 2*atan(l/2d)


with this formula I can calculate the horizontal field-of-view of my camera.



I found it at this site - Determining the viewing angle of your camera


Only I havent a scientific calculator or the where with all to solve this!



I need to find a - the angle of view.
I know that l is the width - 2290mm
and I know that d is the distance - 5000mm


Any help from your forum members would be great! please save me any more days trawling endless websites trying to make sense of this!


Thanks
JayT










]]> Trigonometry mrtea http://www.mathhelpforum.com/math-help/f14/help-simple-goniometrics-155228.html trig identities help needed http://www.mathhelpforum.com/math-help/f14/trig-identities-help-needed-155210.html Sun, 05 Sep 2010 02:11:12 GMT so i have my end of prelims coming up and doing a revision test. this question came up prove (sec^2x - 1)cos^2x = sin^2x Now i thought that you would do the question like this: LHS = (sec^2x-1)cos^2x = (Tan^2x)cos^2x = \frac{\sin^2x}{cos^2x} cos^2x... so i have my end of prelims coming up and doing a revision test. this question came up


Now i thought that you would do the question like this:



but it gave a different soln. am i wrong? ]]> Trigonometry link0099 http://www.mathhelpforum.com/math-help/f14/trig-identities-help-needed-155210.html <![CDATA[[SOLVED] some more trig identities]]> http://www.mathhelpforum.com/math-help/f14/some-more-trig-identities-155204.html Sat, 04 Sep 2010 22:57:35 GMT hi. I think i'm getting the hang of these problems but I still need some assistance:

1)




2)




3)
???

are 1 and 2 correct? number 2 I wasn't sure about (sinx)^2=1/4 - - - sinx=1/2. can i just do a square root like that? and how do I solve 3?

Thanks ]]> Trigonometry jayshizwiz http://www.mathhelpforum.com/math-help/f14/some-more-trig-identities-155204.html