finding the second coordinate

[Ashutosh Iddya]

HI,

How do you find the other endpoint of a line given one endpoint and the
slope of the line.

Also how do you display the coordinate on the computer screen knowing
that the Y axis (of the raster display) runs in the reverse direction of
a normal graph.
ex: given two points
x1 = 100
y1 = 600

and given an angle
45 degrees ie the slope(m)of the line is 1
and given the distance of 206 units
how do I find x2 and y2(the other endpoint of the line)?

how do i display it on the computer screen.

thanks,
Ashutosh

[John Harrison]

"Ashutosh Iddya" <u2******@anu.edu.au> wrote in message
news:3f********@clarion.carno.net.au...

HI,

How do you find the other endpoint of a line given one endpoint and the
slope of the line.

Also how do you display the coordinate on the computer screen knowing
that the Y axis (of the raster display) runs in the reverse direction of
a normal graph.
ex: given two points
x1 = 100
y1 = 600

and given an angle
45 degrees ie the slope(m)of the line is 1
and given the distance of 206 units
how do I find x2 and y2(the other endpoint of the line)?

how do i display it on the computer screen.

thanks,
Ashutosh

You need trigonometry, doesn't that get taught in schools any more?

radians = 45*PI/180;
x2 = x1 + 206*cos(radians);
y2 = y1 + 206*sin(radians);

You might need to change a + to a - depending on which way your axis goes.

Note that I convert 45 degrees to radians because sin and cos in C++ need an
angle in radians not degrees.

john

[Alf P. Steinbach]

On Thu, 04 Sep 2003 16:25:12 +1000, Ashutosh Iddya <u2******@anu.edu.au> wrote:

How do you find the other endpoint of a line given one endpoint and the
slope of the line.
Sorry, that's not a C++ question.

Consult your primary school / secondary school / high school math
textbook (depending on the country), or try some other newsgroup.
Also how do you display the coordinate on the computer screen knowing
that the Y axis (of the raster display) runs in the reverse direction of
a normal graph.

In C++, use a graphics / GUI library.

There are quite a number of free, cross-platform C++ graphics / GUI
libraries.

A short list of free GUI libraries is available at
[http://www.utvikling.com/cppfaq/04/05/01/index.html].

[John Harrison]

"Alf P. Steinbach" <al***@start.no> wrote in message
news:3f**************@News.CIS.DFN.DE...

On Thu, 04 Sep 2003 16:25:12 +1000, Ashutosh Iddya <u2******@anu.edu.au> wrote:

How do you find the other endpoint of a line given one endpoint and the
slope of the line.

Sorry, that's not a C++ question.

Consult your primary school / secondary school / high school math
textbook (depending on the country), or try some other newsgroup.

High school text book is unlikely to tell him that he needs to convert his
angle to radians.

john

[Alf P. Steinbach]

On Thu, 4 Sep 2003 07:35:41 +0100, "John Harrison" <jo*************@hotmail.com> wrote:

"Alf P. Steinbach" <al***@start.no> wrote in message
news:3f**************@News.CIS.DFN.DE...

On Thu, 04 Sep 2003 16:25:12 +1000, Ashutosh Iddya <u2******@anu.edu.au>

wrote:

>How do you find the other endpoint of a line given one endpoint and the
>slope of the line.

Sorry, that's not a C++ question.

Consult your primary school / secondary school / high school math
textbook (depending on the country), or try some other newsgroup.

High school text book is unlikely to tell him that he needs to convert his
angle to radians.

<ot>
My secondary school math textbook did (around 1978 or something).

But I thought the level in both secondary school and high school was
extremely low, and had been going downhill for some time, judging from
my sister's books (she's three years older) and my mother's books.

Education system is all downhill, at least in Norway... :-(
</ot>

[John Harrison]

"Alf P. Steinbach" <al***@start.no> wrote in message
news:3f**************@News.CIS.DFN.DE...

On Thu, 4 Sep 2003 07:35:41 +0100, "John Harrison" <jo*************@hotmail.com> wrote:

"Alf P. Steinbach" <al***@start.no> wrote in message
news:3f**************@News.CIS.DFN.DE...

On Thu, 04 Sep 2003 16:25:12 +1000, Ashutosh Iddya <u2******@anu.edu.au>

wrote:

>How do you find the other endpoint of a line given one endpoint and

the >slope of the line.

Sorry, that's not a C++ question.

Consult your primary school / secondary school / high school math
textbook (depending on the country), or try some other newsgroup.

High school text book is unlikely to tell him that he needs to convert

hisangle to radians.

<ot>
My secondary school math textbook did (around 1978 or something).

Amazing! It told you that the C standard library math routines require
angles in radians. I guess that was what set you on your path to become a
programmer.
But I thought the level in both secondary school and high school was
extremely low, and had been going downhill for some time, judging from
my sister's books (she's three years older) and my mother's books.

Education system is all downhill, at least in Norway... :-(
Same in the UK.
</ot>

john

[Sona]

Ashutosh Iddya wrote:

HI,

How do you find the other endpoint of a line given one endpoint and the
slope of the line.
The way you found the startpoint and the equation of the line.

Also how do you display the coordinate on the computer screen knowing
that the Y axis (of the raster display) runs in the reverse direction of
a normal graph.

Depends. For example, if you're programming a toaster, then you don't
have to worry about the display.

ex: given two points
x1 = 100
y1 = 600

and given an angle
45 degrees ie the slope(m)of the line is 1
and given the distance of 206 units
how do I find x2 and y2(the other endpoint of the line)?
If you knwo it's 206 units and you know the slope and the equation of
the line, what more do you need to know to get to the other end? If all
fails, try a bicyle!

how do i display it on the computer screen.

thanks,
Ashutosh

Sona