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# Sin and Cos. how do i use them in C++

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ok i need to find the height of a qudralateral using only the measurements of the sides and the angles. some how i need to use sin and cos yet i;ve never used any of those type of equations in C++ is it possible? how? also i''ve never really used cos and sin on a calculator so i have no clue how to even setup the equation. all i know is sin and cos find the langth of the oppsite and the adjacent using the hypotenuse and the other given side.

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float x = cos(angle);

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yeh and don''t forget... #include <math.h>

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And don't forget the angle is measured in radians. To convert degrees to radians, multiply it by Pi/180. To convert from radians to degrees multiply by the inverse (180/Pi).

EDIT: and if you are using C++, you should include not math.h

[edited by - YoshiN on November 17, 2003 1:59:52 PM]

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quote:
Original post by YoshiN
EDIT: and if you are using C++, you should include not math.h

Whats the difference?

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quote:
Original post by SpaceDude
Whats the difference?

math.h is a depreciated header. if you''re using c++ you should be using cmath (no .h)

-eldee
;another space monkey;
[ Forced Evolution Studios ]

Do NOT let Dr. Mario touch your genitals. He is not a real doctor!

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quote:
Original post by eldee
quote:
Original post by SpaceDude
Whats the difference?

math.h is a depreciated header. if you''re using c++ you should be using cmath (no .h)

Got any more info on that? I''m interested to know what the actual difference is...

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quote:
Original post by SpaceDude
quote:
Original post by eldee
quote:
Original post by SpaceDude
Whats the difference?

math.h is a depreciated header. if you''re using c++ you should be using cmath (no .h)

Got any more info on that? I''m interested to know what the actual difference is...

The difference is that cmath adds a few extra #defines and stuff. If you want specifics, just open cmath from your C++ compiler''s include folder. You''ll notice that it actually includes the math.h header.

"Skepticism.... that great rot of the intellect." - V.H.
Bah, what does HE know?

Albekerky Software

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Actually, the differences are that <math.h> is deprecated and with <cmath> all symbols are under the std namespace.

http://www.cplusplus.com/doc/ansi/hfiles.html

[edited by - Alvaro on November 17, 2003 9:47:13 PM]

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Also, cmath overloads the functions so calling cos() with a float parameter actually calls cosf()

VERY useful for templates.

- Scott "me22" McMurray
( email/MSN me22@fastmail.ca ICQ 37213887 )

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math.h isn''t part of the C++ standard is what the difference is. However, it is part of the C standard so I believe you can be guaranteed that the contents of math.h are the same throughout different implimentations.

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ok so heres what i should do from what i got out of your posts

#include <cmath>

main ()
{
double I;// length of hypotenuse
double E;// equals the angle
double ans;
cin >> E;

ans=cos(E);
}

ok so what about the hypotenuse where does that come into play. the object of using sin and cos, is to figure out the hieght of a paralellagram by using only the measurements of it's angles and sides like this:
12
________________
\|\x|\9
\|\
`\___________|___\ a:60 degrees

how do i find x?

[edited by - barrager on November 18, 2003 11:16:38 AM]

[edited by - barrager on November 18, 2003 11:19:02 AM]

[edited by - barrager on November 18, 2003 11:20:29 AM]

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h/sin60 = hip/sin90

hip="hipotenuse"
h = height

The Sin Law.

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cos(a) = adj/hyp. You know the angle and the hypotenuse, so you need to solve for the adjacent side.

However, because the computer uses radians in your program it should be:

x = 9*cos(Pi/3)

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ok roger that.. eldee threw me off by saying depreciated and not depricated lol...

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quote:
Original post by YoshiN
cos(a) = adj/hyp. You know the angle and the hypotenuse, so you need to solve for the adjacent side.

However, because the computer uses radians in your program it should be:

x = 9*cos(Pi/3)

actually it''s 9*sin60, he wants the height,so it''s the opposite side,not the adjacent.

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quote:
Original post by hpolloni
quote:
Original post by YoshiN
cos(a) = adj/hyp. You know the angle and the hypotenuse, so you need to solve for the adjacent side.

However, because the computer uses radians in your program it should be:

x = 9*cos(Pi/3)

actually it''s 9*sin60, he wants the height,so it''s the opposite side,not the adjacent.