Calculate coordinate from starting point, having distance and an angle for all quadrants

Question

I have:

private double AngleToRadians(double angle)
{
     return (Math.PI / 180) * angle;
}


double x = 30, y = 60;
var dist = 10;
var angle = 120;

x = x + dist * Math.Cos(AngleToRadians(angle));
y = y + dist * Math.Sin(AngleToRadians(angle));

What this does is returns me a new coordinate, 10 points into direction (angle) from (x,y) starting point.

This works correctly in top-right quadrant, but does not on any of other three.

Is there a formula that would work in all 4?

It works fine on top-right quadrant only. It fails on any other, probably 40* off or something. — user2818626, Nov 03 '15 at 20:42
Does `AngleToRadians` work properly? Can you include that code? — ryanyuyu, Nov 03 '15 at 20:42
what if you do this instead for you `angle` `var angle = 120.0;` checkout the `Math Sin` Math.Sin documentation MSDN](https://msdn.microsoft.com/en-us/library/system.math.sin(v=vs.110).aspx) [Math.Cos MSDN](https://msdn.microsoft.com/en-us/library/system.math.cos(v=vs.110).aspx) — MethodMan, Nov 03 '15 at 20:47
How are you determining that this doesn't work in other quadrants? — Kyle, Nov 03 '15 at 20:49
@user2818626 test the values themselves on your platform, in a new solution/project or something — , Nov 03 '15 at 20:54
"top-right" quadrant is ambiguous until you tell us whether y increases going up or down — samgak, Nov 04 '15 at 04:46

score 7 · Answer 1 · answered Nov 04 '15 at 07:22

x = x + dist * Math.Cos(AngleToRadians(angle)); y = y + dist * Math.Sin(AngleToRadians(angle));

It seems you are using the same x and y variables both for central point and for ending point, so coordinates of center are updated every time

Just use x0, y0 as center and x, y as ending point

x = x0 + dist * Math.Cos(AngleToRadians(angle));

score -2 · Answer 2 · answered Aug 21 '19 at 13:18

a (horizontal length), b (vertical length), x (coordinate x), y (coordinate y), r (radius of the sphere), θ (angle), L (distance until the ball stops) are given, find coordinates (X, Y) at which the ball stops.

Tips:

If the billiard table is infinitely large and the ball can not reach to wall, then calculated, the coordinates (X, Y) at which the ball stops can be calculated by the following formula. X = L * cos (θ) + x Y = L * sin (θ) + y

Calculate coordinate from starting point, having distance and an angle for all quadrants

2 Answers2

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