Calculate the angle between the straight line and the horizontal axis in the program

In programming languages, determining the angle between a straight line and a horizontal axis is crucial for various graphical operations. Given two points: (P1x, P1y) and (P2x, P2y), let us explore a simple and efficient way to calculate this angle.

step:

1. Calculate the difference vector (DeltaX, DeltaY):

   • deltaX = P2x - P1x
   • deltaY = P2y - P1y

2. Determine the angle:

   • General situation:

     • angleInDegrees = arctan(deltaY/deltaX) * 180/PI

   • Improve the accuracy (using the atan2 function):

     • angleInDegrees = atan2(deltaY, deltaX) * 180 / PI

Other precautions:

1. Determine quadrant:

   • The symbols of deltaX and deltaY will indicate the quadrant where the angle is.
   • Positive deltaX and deltaY represent angles between 0 and 90 degrees, negative deltaX and deltaY represent angles between 180 and 270 degrees, and so on.

2. Normalization (optional):

   ]
   • By dividing deltaX and deltaY by the length of the vector (sqrt(deltaX^2 deltaY^2)), you can get unit vectors representing the cosine and sine of the angle. This step simplifies the calculation and avoids potential zero division.

Example:

import math

def calculate_angle(P1x, P1y, P2x, P2y):
  deltaX = P2x - P1x
  deltaY = P2y - P1y
  angle = math.atan2(deltaY, deltaX) * 180 / math.pi
  return angle

in conclusion:

Use the provided method, you can accurately calculate the angle between the straight line and the horizontal axis. This algorithm is simple and efficient, allowing you to implement it in a variety of programming languages ​​for graphics applications or geometric calculations.