% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/proportional.R
\name{circle_intersection_area}
\alias{circle_intersection_area}
\title{Lens-shaped intersection area of two circles}
\usage{
circle_intersection_area(r1, r2, d)
}
\arguments{
\item{r1}{Radius of circle 1 (positive numeric).}

\item{r2}{Radius of circle 2 (positive numeric).}

\item{d}{Distance between centers (non-negative numeric).}
}
\value{
Numeric: 0 if circles are disjoint, pi * min(r1,r2)^2 if fully nested,
  else the lens-shaped intersection area.
}
\description{
Mirrors `src/utils/proportionalLayout.ts circleIntersectionArea` (web tool)
and Python `circle_intersection_area` byte-for-byte.
}
\examples{
circle_intersection_area(1, 1, 1)   # ~ 1.228
circle_intersection_area(1, 1, 3)   # 0 (disjoint)
}
