Math Is Fun Forum

Aartt

Member

Registered: 2010-12-14

Posts: 136

Re: Sin, Cos, and Tan

oh woops lemme find x for fun so x = 17320.50808

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Im a 6th grader(ya your all thinking what is he doing here. My answer is I <3 Math and i cannot get enough) I also like Science like Chemistry and Physics(even though i know about nothing about them i still love them because the include the word "MATH" )

Aartt

Member

Registered: 2010-12-14

Posts: 136

Re: Sin, Cos, and Tan

well gtg now for today bye

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Im a 6th grader(ya your all thinking what is he doing here. My answer is I <3 Math and i cannot get enough) I also like Science like Chemistry and Physics(even though i know about nothing about them i still love them because the include the word "MATH" )

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Sin, Cos, and Tan

Okay, see you tomorrow.

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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.

Aartt

Member

Registered: 2010-12-14

Posts: 136

Re: Sin, Cos, and Tan

ok im back yay

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Im a 6th grader(ya your all thinking what is he doing here. My answer is I <3 Math and i cannot get enough) I also like Science like Chemistry and Physics(even though i know about nothing about them i still love them because the include the word "MATH" )

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Sin, Cos, and Tan

The biggest slide in the world drops 213 meters in a horizontal distance of 1200 meters.

a) How long is that slide?

b) What is its angle of inclination?

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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.

Aartt

Member

Registered: 2010-12-14

Posts: 136

Re: Sin, Cos, and Tan

so im gonna do (b) first and so im gonna use TOA because i know the adj and opp and im trying to find the angle so the formula for tan is Opp/Adj = Tan(x) so to replace the vars it would be 213/1200 =  Tan(x) now i figure out what the tan of x equals and it would be 0.1775 so now i click Tan-¹ which equals 10.06 so the x angle equals 10.06°(not rounded) now to (a)

So im gonna use the formula that bob bundy gave me Adj/Cos(angle) = Hyp so replace the vars and i get 1200/Cos(10.06) = Hyp so the hypotenuse equals 1218.75m

am i right?

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Im a 6th grader(ya your all thinking what is he doing here. My answer is I <3 Math and i cannot get enough) I also like Science like Chemistry and Physics(even though i know about nothing about them i still love them because the include the word "MATH" )

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Sin, Cos, and Tan

Hi;

Yes that is correct, except for your rounding. If you are truncating to 2 digits after the decimal that is fine. If I asked you to round to 2 digits after the decimal what would you get?

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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.

Aartt

Member

Registered: 2010-12-14

Posts: 136

Re: Sin, Cos, and Tan

huh 2 digits after the decimal? um for a or b for a it would be 1200m right?

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Im a 6th grader(ya your all thinking what is he doing here. My answer is I <3 Math and i cannot get enough) I also like Science like Chemistry and Physics(even though i know about nothing about them i still love them because the include the word "MATH" )

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Sin, Cos, and Tan

No for your answer, the angle and the length of the slide.

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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.

Aartt

Member

Registered: 2010-12-14

Posts: 136

Re: Sin, Cos, and Tan

huh so like round to the 10 place? plz can you tell me in a diffrent form like which significant numbers you want?

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Im a 6th grader(ya your all thinking what is he doing here. My answer is I <3 Math and i cannot get enough) I also like Science like Chemistry and Physics(even though i know about nothing about them i still love them because the include the word "MATH" )

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Sin, Cos, and Tan

Hi;

I am not making it clear. Round these to 2 places after the decimal.

10.06516° and 1218.75715 meters.

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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.

Aartt

Member

Registered: 2010-12-14

Posts: 136

Re: Sin, Cos, and Tan

ook so that would be the answer how is that 2 digits from the decimal?

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Im a 6th grader(ya your all thinking what is he doing here. My answer is I <3 Math and i cannot get enough) I also like Science like Chemistry and Physics(even though i know about nothing about them i still love them because the include the word "MATH" )

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Sin, Cos, and Tan

I would like you to round those 2 numbers to 2 places after the decimal point.

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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.

Aartt

Member

Registered: 2010-12-14

Posts: 136

Re: Sin, Cos, and Tan

kk but that is rounding 5 decimal places

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Im a 6th grader(ya your all thinking what is he doing here. My answer is I <3 Math and i cannot get enough) I also like Science like Chemistry and Physics(even though i know about nothing about them i still love them because the include the word "MATH" )

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Sin, Cos, and Tan

That is not important, they were actually truncated instead of rounded and we are going to go over both types and a guy named Pythagoras.

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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.

Aartt

Member

Registered: 2010-12-14

Posts: 136

Re: Sin, Cos, and Tan

ok go ahead and i dont know what truncated means?

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Im a 6th grader(ya your all thinking what is he doing here. My answer is I <3 Math and i cannot get enough) I also like Science like Chemistry and Physics(even though i know about nothing about them i still love them because the include the word "MATH" )

Au101

Member

Registered: 2010-12-01

Posts: 353

Re: Sin, Cos, and Tan

Hi Aartt, to truncate something is literally to shorten, or to cut off. So, if you truncate a decimal, e.g. 0.7456464, you simply shorten it, without regard to rounding, i.e. 0.745 would be a truncation of that decimal.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Sin, Cos, and Tan

10.06516° and 1218.75715 meters.

To truncate 10.06516° to 2 places after the decimal ( always referring to digits on the right of the decimal point ). You just drop everything after the second digit.

To round to 2 places after the decimal. You look at the next digit. 5 or more go up, 4 or less go down.

I did not see Au101's answer which is correct. Now you can do the 1218.75715 meters by yourself.

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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.

Aartt

Member

Registered: 2010-12-14

Posts: 136

Re: Sin, Cos, and Tan

oh so i shouldnt have truncated?

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Im a 6th grader(ya your all thinking what is he doing here. My answer is I <3 Math and i cannot get enough) I also like Science like Chemistry and Physics(even though i know about nothing about them i still love them because the include the word "MATH" )

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Sin, Cos, and Tan

Different point, you are remembering the other problem. Forget it for right now and try to work on the new one. You have a number to truncate and round. 2 posts have given you the means.

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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.

Aartt

Member

Registered: 2010-12-14

Posts: 136

Re: Sin, Cos, and Tan

what new one?

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Im a 6th grader(ya your all thinking what is he doing here. My answer is I <3 Math and i cannot get enough) I also like Science like Chemistry and Physics(even though i know about nothing about them i still love them because the include the word "MATH" )

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Sin, Cos, and Tan

Please round to 2 places after the decimal point.

1218.75715 meters.

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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.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,621

Re: Sin, Cos, and Tan

hi Aartt,

Sorry I've not contributed to this thread for a while.  I was out for a whole day and then, when I looked, you seems to be progressing well with your trig. 

Now you seem to be hung up on rounding off.

So, maybe a little lesson in that will help.

I'm going to look at the decimal number 1.817

Here's a picture that shows where it is on the number line.

Firstly, the gap between 1 and 2 is divided into tenths.  Our number is over 1.8 but under 1.9

Then, the diagram is magnified by x 10 so you can see the hundredths.

Our number is between 1.81 and 1.82

Then the diagram is magnified by x 10 again to show the thousandths.

Our number can now be shown exactly as 1 unit, 1 tenth, 8 hundredths and 7 thousandths.

Now for the rounding off.

If you truncate the number you just chop off unwanted digits so you'd get 1.81

But the diagram shows that 1.817 is nearer to 1.82 so this is the correct thing to write if you are rounding.

I've seen you write the rule for this in post 99

because the digit behind it is greater than 4 so you up the number in front of it by one

But why this rule?

Because you're looking to see which way is nearer;
4 and below means 'to the left' is nearer;  this is ROUNDING DOWN
above 4 means 'to the right is nearer;  this is ROUNDING UP.

There are many ways to ask someone to round off:

Give answer to 2 decimal places
Give answer to 3 significant figures
Round to the nearest whole number
etc etc.

Does that help?

Footnote.  It's 3.16am, here in England.  I woke up and couldn't sleep so I thought I'd have a look at MIF.

I think there's a big time difference between us, which is why you sometimes post and then wonder why there's no reply for a while.  Tell me what your screen says for the time I posted this and we can work out the time zone difference.
Bob

Last edited by Bob (2010-12-18 15:24:37)

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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

Aartt

Member

Registered: 2010-12-14

Posts: 136

Re: Sin, Cos, and Tan

well i it dosent tell the right time for me on the forum but i live in washinton and right now its about 8 pm and whats MIF?

Last edited by Aartt (2010-12-18 16:05:24)

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Im a 6th grader(ya your all thinking what is he doing here. My answer is I <3 Math and i cannot get enough) I also like Science like Chemistry and Physics(even though i know about nothing about them i still love them because the include the word "MATH" )

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Sin, Cos, and Tan

MathsIsFun!

Is that Washington D.C.?

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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.