input geometriesyr16; beginfig(1); pair A,B,C,D,I,J,K,L; A=u*(1,1); B=u*(5,1.5); C=A rotatedabout(B,-90); D=B rotatedabout(A,90); trace A--B--C--D--cycle; path astro; I=1/2[A,B]; J=1/2[B,C]; K=1/2[C,D]; L=1/2[D,A]; astro=J--arccercle(J,I,B)--arccercle(I,L,A)--arccercle(L,K,D)--arccercle(K,J,C)--cycle; trace hachurage(astro,60,0.25,1); trace astro; trace cotation(A,B,-4mm,-2mm,btex $2c$ etex); trace codesegments(A,I,I,B,2); trace codesegments(B,J,J,C,2); trace codesegments(C,K,K,D,2); trace codesegments(D,L,L,A,2); trace codeperp(A,B,C,5); trace codeperp(B,C,D,5); trace codeperp(C,D,A,5); endfig; end