Triangle Survey Distance Calculator

Method, example, and limits

Formula: c = √(a² + b² − 2ab cos θ), the law of cosines.

Inputs and units: a and b are measured sides, θ is their included angle in degrees, and c is the opposite side. Keep length units consistent.

Worked example: For sides 3 m and 4 m with an included angle of 90°, c = 5 m.

Result meaning: c is the direct endpoint-to-endpoint separation opposite the included angle, not the sum of the two station distances.

Assumptions: The entered angle is the included interior angle between the two measured rays. Inputs describe a planar triangle; values are not adjusted for measurement error or earth curvature.

Limits: This computes geometry, not a surveying adjustment. It does not account for slope-to-horizontal reduction, datum, instrument calibration, or uncertainty; choose another method if those matter.