Znanstvenostručni
časopis Hrvatskog društva za geometriju i grafiku Scientific and Professional Journal 
 Zdenka KolarBegović (zkolar@mathos.hr)
Icosahedron Inscribed in an Affine Regular Octahedron in a GSQuasigroupA golden section quasigroup or shortly a GSquasigroup
is an idempotent quasigroup which satisfies the identities 
 Harun Bariş Çolakoğlu (hbcolakoglu@akdeniz.edu.tr)
Trigonometric Functions in the mplaneIn this paper, we define the trigonometric functions in the
plane with the mmetric. And then we give two properties
about these trigonometric functions, one of which states
the area formula for a triangle in the mplane in terms of
the mmetric. 
Ema Jurkin, Marija Šimić Horvath, Vladimir Volenec (ema.jurkin@rgn.hr, marija.simic@arhitekt.hr, volenec@math.hr)
On Brocard Points of Harmonic Quadrangle in Isotropic PlaneIn this paper we present some new results on Brocard points of a harmonic quadrangle in isotropic plane. We construct new harmonic quadrangles associated to the given one and study their properties dealing with Brocard points.

 Iva Kodrnja, Helena Koncul (ikodrnja@grad.hr, hkoncul@grad.hr)
The Loci of Vertices of Nedian TrianglesIn this article we observe nedians and nedian triangles of
ratio \(\eta\) for a given triangle. The locus of vertices of the
nedian triangles for \(\eta\in \mathbb{R}\) is found and its correlation with isotomic
conjugates of the given triangle is shown. Furthermore, the curve on which lie vertices of a nedian triangle for
fixed \(\eta\), when we iterate nedian triangles, is found. 
 Gunter Weiss (weissgunter@hotmail.com)
Nonstandard Aspects of Fibonacci Type SequencesFibonacci sequence and the limit of the quotient of adjacent Fibonacci numbers, namely the Golden Mean, belong to general knowledge of almost anybody, not only of mathematicians and geometers. There were several attempts to generalize these fundamental concepts which also found applications in art and architecture, as e.g. number series and quadratic equations leading to the socalled "Metallic means" by V. DE SPINADEL [8] or the cubic "plastic number" by VAN DER LAAN [5] resp. the "cubi ratio" by L. ROSENBUSCH [7]. The mentioned generalizations consider series of integers or real numbers. "Nonstandard aspects" now mean generalizations with respect to a given number field or ring as well as visualizations of the resulting geometric objects. Another aspect concerns Fibonacci type resp. Padovan type combinations of given start objects. Here it turns out that the concept "Golden Mean" or "van der Laan Mean" also makes sense for vectors, matrices and mappings. 
 Boris Odenhal (boris.odehnal@uniak.ac.at)
Generalized ConchoidsWe adapt the classical definition of conchoids as known from the Euclidean plane to geometries that can be modeled within quadrics. Based on a construction by means of cross ratios, a generalized conchoid transformation is obtained. Basic properties of the generalized conchoid transformation are worked out. At hand of some prominent examples  line geometry and sphere geometry  the actions of these conchoid transformations are studied. Linear and also nonlinear transformations are presented and relations to wellknown transformations are disclosed.

 Norman J. Wildberger (n.wildberger@unsw.edu.au)
Rational Trigonometry in Higher Dimensions and a Diagonal Rule for 2planes in Fourdimensional SpaceWe extend rational trigonometry to higher dimensions by introducing rational invariants between ksubspaces of ndimensional space to give an alternative to the canonical or principal angles studied by Jordan and many others, and their angular variants. We study in particular the cross, spread and detcross of 2subspaces of fourdimensional space, and show that Pythagoras theorem, or the Diagonal Rule, has a natural generalization for such 2subspaces.

Bojan Janjanin, Jelena BebanBrkić (janjanin.bojan@gmail.com,
jbeban@geof.hr)
Survey Analysis of the Great PyramidThe topic of this paper is an analysis of the survey of Cheops pyramid (also known as the Great pyramid), the most significant of the three pyramids of the Giza complex, the archeological site on the plateau of Giza, situated on the periphery of Cairo. It is assumed that Cheops as well as Khafre and Menkaure pyramids were built around 2686  2181 BC, known in the history as the Old Kingdom of Egypt. Our goal was to collect data about geodetic survey of Cheops pyramid and analyze it. Along with that, several hypotheses related to the construction method of the pyramid and possible purposes of the construction itself are described. When analyzing the survey, two numbers, also called "two treasures of geometry", are constantly appearing, these are the number Pi (\(\pi\)) and the Golden ratio or golden number Fi (\(\varphi\)). One of the chapters is dedicated to these numbers.
