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Calculate Slope of A Line in Degrees

Reviewed by Calculator Editorial Team

Calculating the slope of a line in degrees is essential in geometry, physics, and engineering. This calculator helps you determine the angle of inclination of a line using the arctangent function.

What is Slope?

Slope is a measure of the steepness and direction of a line. It is often represented by the letter "m" and is calculated as the ratio of the vertical change (rise) to the horizontal change (run) between two points on the line.

Slope Formula: m = (y₂ - y₁) / (x₂ - x₁)

The slope can be positive, negative, zero, or undefined. A positive slope indicates an upward trend, while a negative slope indicates a downward trend. A zero slope means the line is horizontal, and an undefined slope means the line is vertical.

Slope in Degrees

While slope is typically expressed as a ratio, it can also be converted to degrees to represent the angle of inclination of the line. This is particularly useful in fields like physics and engineering where angles are more intuitive.

Angle of Inclination Formula: θ = arctan(m) × (180/π)

The arctangent function (arctan) converts the slope ratio to an angle in radians, which is then converted to degrees by multiplying by 180/π.

Note: The angle of inclination ranges from -90° to 90°. A positive angle indicates the line rises to the right, while a negative angle indicates it falls to the right.

How to Calculate the Slope in Degrees

  1. Identify two points on the line: (x₁, y₁) and (x₂, y₂).
  2. Calculate the slope (m) using the formula: m = (y₂ - y₁) / (x₂ - x₁).
  3. Convert the slope to degrees using the formula: θ = arctan(m) × (180/π).
  4. Interpret the result: a positive angle means the line rises to the right, while a negative angle means it falls to the right.

Example Calculation

Let's calculate the slope of a line passing through the points (2, 3) and (5, 7) in degrees.

  1. Calculate the slope: m = (7 - 3) / (5 - 2) = 4 / 3 ≈ 1.333.
  2. Convert to degrees: θ = arctan(1.333) × (180/π) ≈ 53.13°.

The line has an angle of inclination of approximately 53.13 degrees.

FAQ

What is the difference between slope and angle of inclination?

Slope is a ratio that measures the steepness of a line, while the angle of inclination is the angle that the line makes with the positive direction of the x-axis. They are related through the arctangent function.

Can the angle of inclination be greater than 90 degrees?

No, the angle of inclination ranges from -90° to 90°. Lines with angles outside this range are not possible in standard Cartesian coordinates.

How do I calculate the slope if I only have the angle of inclination?

You can use the tangent function: m = tan(θ × (π/180)).