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#26 Re: Help Me ! » Anyone know sheets of math assignments? Or a book? » 2014-08-01 01:46:13
In my experience, drilling in math by doing routine problems will get you an A+ in high school, but won't give you a mastery of the subject.
Very true, but there is not often enough time ( during the school time) to search for the proof or understand the proof. We are just sheeps that need to do something without asking why! The fun stuff is always after school time (: And having the skills to solve an equation with a certain ease is always handy (:
But I think I just rince and repeat the stuff that I have...
#27 Re: Help Me ! » Trigonometry proof of formula » 2014-07-31 01:47:58
Sometimes I am awestruck by mathematics, I just can't understand how it can be so consistent! Sometimes (even with quantum mechanics (what I definetely don't understand) I sometimes think that we create the reality, because math is build of axioms and definitions. I don't know... for now I will stay awestruck and hope I will be as good as the people on this forum (:
The compound angles is something that I have to learn (should know it a lot better than I do now) too. I want to know why it is like that and not just put it in the TI-84 and be done with it. I understand the unit circle a little bit better now, but still triangles and same points even though it looks different, still is a little bit...
I know that people that work with land use a different kind of ... angles ? Like I believe they have circles of 420 degrees? Don't know.
So the unit circle is a more general theorie of the sine, cosine and tangent? Would you say that the ''normal sine, cosine and tangent'' are incorporated in the unit circle?
#28 Re: Help Me ! » Anyone know sheets of math assignments? Or a book? » 2014-07-31 01:29:53
Post the link please.
http://www.schoolhousetech.com/
I believe this is pre-calculus but it is for teachers only!
http://www.math-drills.com/
This is also a nice page, but again for pre-calculus.
http://themathworksheetsite.com/
Pre-calculus
Those two above is what I kind of like, but it is too easy for me to do (:
https://www.kutasoftware.com/
Seems reasonable... It is only after two weeks for a big fee! (haven't tried it yet)
I Also have a book, but it is Dutch... and there are no assignments about primitive functions (dunno if it is the name) It is the opposite of differentiation.
#29 Re: Help Me ! » Anyone know sheets of math assignments? Or a book? » 2014-07-30 19:23:38
Spivak Calculus (available online). Do one chain rule problem from it and you're done.
Mwhuahha, Thank you! But I am more or less searching for mere assignments (: for practising my skills.
Just the exercise not the theory. I have a few math books with just exercises but, my problem is, when I have done a few I remember the answers so I kinda know where to work to (:
I just want a sheet filled with nice math and answers ofcourse! Like 2000 assignments on one page (: Would be awesome yes?
Sorry Guys, I googled just now and I think I found something (:
Sorry for opening topic, before researching!
#30 Re: Help Me ! » Trigonometry proof of formula » 2014-07-30 08:38:03
I have read it (: I will respond tomorrow (: (:
#31 Help Me ! » Anyone know sheets of math assignments? Or a book? » 2014-07-30 07:33:44
- Whizzies
- Replies: 7
Heyy people,
I am searching for a book or sheets with lots of lots of assignments. Differentiating and integrating primitives and such. I'd like to be more natural in using the chain rule product rule and using that with primitives. (:
Thanks!
I rather have not some random computer giving assignments. I want the answers too. Like calc the primitive of Ln(2x-2) and differentiate 20log(x-20) and such (:
#32 Re: Help Me ! » Trigonometry proof of formula » 2014-07-28 22:34:35
I think it's worse than tedious. You would have to create three right angled triangles in one diagram, and chase around all the distances. Possible, but not nice.
I cannot think of an easy way to do with a diagram.
Bob
Yes, I tried to do it but I got confused so I gave up and asked you if it were possible and your answer explains my confusion (:
Could you also explain maybe what the unit circle is exactly? I know the ''drill'' but what is it? If I were to have a right triangle (the special ones with the nice rations) then I would understand how handy it is.
I once saw on youtube how triangles are so nice! They support bridged and make you able to measure up distances. I believe even on schips (in the old days) they had a telescope that measures things with triangles, but what is the use of the unit circle?
#33 Re: Help Me ! » Trigonometry proof of formula » 2014-07-27 22:35:28
Thx (:
Would it also be possible to make a diagram here, or is that tedious work?
#34 Re: Help Me ! » Trigonometry proof of formula » 2014-07-27 06:27:41
hi Whizzies
cos (a-0.5pi)=sin(a)
For this you need a diagram like mine, but with the rotation going clockwise rather than anticlockwise.
The 'up' for angle a will become the 'across' for a - 0.5pi in the fourth quadrant.
cos (a-0.5pi) = Qx = Py = sin (a).
is correct.
what is the difference between cos ( pi - a); cos (a - pi) ?
They are the same. Again a diagram will show this. Start with an angle a. Rotate by -pi. This takes the angle from the first into the third quadrant. Now start with angle pi and rotate by -a. This also takes you to the same angle in the third quadrant.
Bob
YES! I am very very happy that I have it right (: Means that I am on the right way!
It is also the case that cos(-a) = cos(a) for any angle a. Can you prove this ? So this last result follows from that.
Bob
cos (-a) = Xq = Xp = cos (a)
I now have to do sin(x + (1/6)pi) = cos (ax + b)
I have to learn these formulas -sin(a) = sin (a +pi) and sin^2(a) + cos^2 = 1 I have 8 bases. Just two are derived and proven, but I really want to understand what I am doing so I have to figure it out. And thanks to this forum and you! I am succeeding (:(:(: I am happy that I found this forum!
First you have to take sin (a+0.5pi) = Yr = Xp = cos (a) and then .. yep still needs some thinking!
PS I am drawing circles and lines to figure it out (:
#35 Re: Help Me ! » Trigonometry proof of formula » 2014-07-27 04:42:26
hé I had to ''proof'' cos (a-0.5pi)=sin(a) (sorry no picture)
Does this 'fit' I had to figure this one out myself because the anwer book has not a explained answer just how it ''is''.
cos (a-0.5pi) = Qx = Py = sin (a).
Point P is in the first quadrant and point Q is in the fourth. If this is correct, I think I get the point! (:
what is the difference between cos ( pi - a); cos (a - pi) ?
#36 Re: Help Me ! » Trigonometry proof of formula » 2014-07-27 03:47:11
http://i.imgur.com/udhAc20.gif
When P is rotated pi/2, that triangle rotates by that amount. The across distance becomes an 'up' distance and the up distance become a negative across distance.
So the Xr coordinate is the same as the Yp coordinate but is now a negative amount
and
the Yr coordinate is the same as the Xp coordinate.
Remember these are just numbers, and those formulas are telling you how one set of numbers is related to another.
So Xr = -Yp and Yr = Xp.
If Yp = 0 (the point MUST be on the circle) so P is the point (1,0). When it rotates pi/2 to point R this is (0,1). So 0 = -0 and 1 = 1. No inconsistency.
Hope that helps,
Bob
WOW! I just... I did not see it that way! it helped a lot! I just... well it is correct; math stills amazes me sometimes how it just 'fits together'! I thank you very much!
btw, I was looking at the coördinates and not the triangle it self (: But when I look at the triangle I understand the .. unity!
#37 Re: Help Me ! » Trigonometry proof of formula » 2014-07-27 00:06:19
Did you try rotating the point on the circle?
B
Yep, but I don't understand this:
Xr = -Yp and Yr = Xp
I also changed my first post! (:
I don't see how Xr = -Yp cause how can X be Y (: And if Y equals zero then X is also zero that would mean it is the origin.
#38 Re: Help Me ! » Trigonometry proof of formula » 2014-07-27 00:00:11
hi Whizzies
Welcome to the forum.
Take a look at this page:
http://www.mathsisfun.com/geometry/unit-circle.html
A short way down the page, you'll find an interactive circle that will help to answer all your questions.
Bob
Hé (: I have been there before. I understand the ''formulas'' in the normal x,y-functions and how to make the cosine into sine and vica versa, but with the unit circle it is a different story (:
#39 Help Me ! » Trigonometry proof of formula » 2014-07-26 23:33:25
- Whizzies
- Replies: 19
Heyy, I am unable to upload a photo so I cannot refer to one.
But I am working on understanding Trig formulas like: sin(-A) = -sin(A).
the book tries to explain it by portraying two unity circles (ill descibe them both).
First figure is a unit circle with a point P in the first quadrant and a point Q in the fourth (those two dots are mirrorring). The angle is called a)
Point Q is the mirror off P in the x-axis so the angle of rotation of Q is -a and Xq = Xp and Yq = -Yp.
So
sin (-a) = Yq = -Yp = -sin(a) and
cos (-a) = Xq = Xp = cos(a)
Yq and Xq the q is meant a s subscript and the Y and X are just normal y and x (sorry I dont know how to subscript).
My question is why is it!! sin (-a) = Yq = -Yp = -sin(a) it should be positive and Yq should be negative right? Why are they turned? I know you could manipulate the equation Yq = -Yp, but that would just make it more complicated 
figured it out! After staring at it for half an hour!
Second question is. a unit circle with Point P (quadrant I, and same spot as the first question) and point R (quadrant 2 and is (a+0.5pi) from point P).
Point R is the image of point B with the roation of 0.5pi rad. Xr = -Yp and Yr = Xp.
So
sin (a+0.5pi) = Yr = Xp = cos (a)
cos (a + 0.5pi) = Xr = -Yp = -sin(a)
I don't uderstand the expression that I made BOLD. Why is Xr = -Yr? Sorry that I am unable to opload the picture so that it would have been easier to explain?
#40 Re: Help Me ! » Algebra Help » 2014-07-26 03:47:59
What is your favourite colour?
lol!
#41 Re: Help Me ! » Sin (x) in triagnle and in the unit circle » 2014-07-20 07:53:02
Sorry that is what I meant! I have a lot of questions hope you don't mind it.
I just found out that the Sine, Cosine, tangent in degrees can also be in radians (they both come on the unit circle).
If I say Sin (30) = 0.5; so: opposite = 1 and hypo = 2. This is an basic triangle just like the 45 degree and 60 degree. What if I take Sin (35), well o/h = 0.5737....
It is not possible to find out what O and H are right? because you have two variables.
#42 Re: Help Me ! » Sin (x) in triagnle and in the unit circle » 2014-07-20 07:33:08
So it is a very very small rectangualr triangle?
#43 Re: Help Me ! » Sin (x) in triagnle and in the unit circle » 2014-07-20 04:15:19
I think that it was originally defined in terms of a circle, that is why they call it a circular function. But it is also called a trigonometric function. The word "Trigonometry" is derived from two Greek words meaning measurement or solution of triangles.
So it is just like the circumference of a circle, when they tried to measure it up. They used squares all around I believe, and they came up with ''pi''. What is the relation between geometry and the unit circle?
What does sin( 1) = o/h = 0.01745... mean? in geometry?
Is there any relation between geometry and trigonometric?
#44 Re: Introductions » Hello Math is fun Forum followers! » 2014-07-20 04:01:43
haha! <
Thanks for the welcomes m8s!
#45 Re: Help Me ! » Sin (x) in triagnle and in the unit circle » 2014-07-20 03:59:25
There are other ways to define the sine function that have nothing to do with circles or triangles.
..... what does it all mean? What does sine mean?
#46 Help Me ! » Sin (x) in triagnle and in the unit circle » 2014-07-20 03:17:50
- Whizzies
- Replies: 9
I am wondering you have the triangles with the definitions of sin (x), cos(x) and tan (x). You can calculate the angle with sin (x) = o /h, but I don't know what sin is. Sin (x) is just a function something that math people decided to do just that? Like Ln (x) ?
What is the difference between sin (x) with the triangles and the radian circle? I am trying to understand what sin (x) means in both of them, the basic figures come back in the Radian circle, but I don't see the connection!?
Sorry the question is some what vague I think, because I don't know how to ask something that I see but don't yet undestand wholly.
#47 Re: Introductions » Hello Math is fun Forum followers! » 2014-07-18 22:17:23
Whizzies wrote:chooipian wrote:Hi;
Nice to meet you, Whizzies! I like maths and physics too. In fact most of us on this forum do.
What's your favourite colour?Haha! I've read a few topics here and you asked others too what their favourite colour is (:
My is I think Grass Green or Sky Blue. What is the reason about it ? (:
Actually, the one who started asking what people's favourite colour is is Agnishom, I just started asking yesterday...
(: Alright!
What are you favourite colours?
#48 Re: Introductions » Hello Math is fun Forum followers! » 2014-07-18 21:42:41
Hi;
Nice to meet you, Whizzies! I like maths and physics too. In fact most of us on this forum do.
What's your favourite colour?
Haha! I've read a few topics here and you asked others too what their favourite colour is (:
My is I think Grass Green or Sky Blue. What is the reason about it ? (:
#49 Introductions » Hello Math is fun Forum followers! » 2014-07-18 21:06:09
- Whizzies
- Replies: 19
Heyyy everbody,
I am new to this forum, I was intrigues by the easy to understand math on the main website, so I thought let's join the forum. I am glad there are a lot of people here, keeps things going.
Last year I learned Eucledian geometry, and I was mind baffled, still am! The way things are reasoned is very logical? I don't know I like it, but also find it very hard to learn. I am more like an algebra person I think, even though the geometry is still so very appealing.
Well! First things first, I am searching for a very good book, but I will open that in a different topic! (:
About me? Well I like physics a lot and physics comes with mathemathics, so its fun! I also like the other sciences! I am very bad at introducting myself (:
So if you have any questions, feel free to ask!
Bye (: