Collinearity Checker
Check whether three points lie on a single straight line.
What is Collinearity?
Three points are collinear when a single straight line passes through all of them. The quickest test is not the slopes — vertical segments have none to compare — but the area of the triangle they span, which is zero exactly when they line up.
How it works
The engine applies the shoelace formula to the three points and reads the answer off the magnitude of the result: zero area means collinear. The same shoelace implementation backs the triangle-area calculator, so the two tools cannot disagree, and the slopes of both segments are reported alongside as a second, more familiar check.
- Enter your input. Type or paste your input into the field above — the tool responds instantly.
- Review the result. Output updates live as you type. Everything runs entirely in your browser.
- Copy or download. Use the Copy button to grab the result, or Download to save it as a file.
Examples
Realistic sample
Type or paste any realistic input — the tool computes the result locally and instantly.
Common mistakes
Expecting a server round-trip
Nothing is uploaded — every tool in this category runs entirely in your browser.