Mathematical Gazette March 2006 Contents Articles Extensions of a theorem of Van Aubel John R. Silvester 2 Products of lengths of line segments associated with elliptical chords Thomas E. Price 13 Numerical integration - a different approach Harry V. Smith 21 Sums of squares of edge-lengths of cyclic polygons John Rigby 25 The distribution of the geometric mean David A. L. Wilson and Barry Martin 40 The sprinkler problem ~ a mathematician waters the lawn Michael A. Jones and Janet L. Stonick 50 Hexagons with opposite sides parallel C. J. Bradley 57 Cassini-like formulas for Jacobsthal and Koshy polynomials Thomas Koshy and Mohammad Salmassi 68 Calculating exact cycle lengths in the generalised Dominic Vella and Alfred Vella 70 Notes 90.01 to 90.30 Fibonacci sequence modulo p Partitioning sets of polygonal numbers Philip Maynard 77 The number of partitions of a number into distinct squares Michael D. Hirschhorn 80 A metric metre Tony Barnard 88 Maths bite: two uses for an algebraic identity Nick Lord 88 Interesting finite and infinite products from simple algebraic identities Thomas J. Osler 90 No converse to an isomorphism theorem Bob Burn 93 A variation on Pythagoras' identity P. Glaister 96 A trigonometrical surprise: Alexander's angles Nick Lord 97 Generalising Alexander's angles Elizabeth M. Glaister and Paul Glaister 99 Could Jonny Griffiths 103 Anthony C. Robin 107 Generalising a 'trigonometric' identity J. K. R. Barnett 110 Square-freedom revisited J. A. Scott 112 Michael D. Hirschhorn 114 Proof with few words: quadratic convergence of the AGM Thomas J. Osler 116 A general version of Simons' integral Anthony Sofo and Rodney Turner 118 be three? A simple approximation to perimeters and polygonal Evaluating Stuart Simons 122 Mean value theorem for integrals generalised to involve two functions Jingcheng Tong 126 A modification of the Newton-Raphson method Stuart Simons 128 Four circles and a triangle Matthew Lee 130 A generalisation of Archimedes' hatbox theorem A generalisation of Archimedes' hatbox theorem 132 A strong result on tiling Roy Barbara 134 Another calculus proof of the location of Fermat's point Jingcheng Tong 135 A right triangle inscribed in a similar right triangle Hiroshi Okumura and Masayuki Watanabe 138 On the evaluation of On the Lester circle, a companion and another special J. A. Scott case 141 Right answer, wrong reason Richard Kirby 143 On the M25 problem John B. Reade 144 How many children? Martin Griffiths 146 Feedback 150 Problem Corner Nick Lord 159 Student Problems Tim Cross 167 Reviews 169 Acknowlegements 191