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2abcA a+b+c A₁ AHKL B₁ bisects centroid circle circumcentre circumcircle circumscribed collinear complementary triangle concyclic congruent conic contour-lines curve D₁ denoted diagonal diameter double point draw drawn Edinburgh Mathematical Society enantiomorph equal excentres excircle FIGURE formed by joining four triangles fundamental triangle Gentleman's Diary Geometry George Watson's College given H₁ Hence incentre incircle inscribed internal bisector intersect Lady's and Gentleman's m₁ Mathematical Master Mathématiques medians meet the circumcircle mid point nine-point circle oppositely situated orthic triangle orthocentre parallel to BC parallelogram passes perpendicular to BC plane point of BC polar Professor proof properties Proposition quadrilateral r₁ radii radius respectively rhombi right angles semiperimeter similar Similarly spherical tangents tartaric acid temperature theorem THOMAS MUIR triangle ABC triangle formed vertex vertices
Page 54 - The diagonals of a quadrilateral intersect at right angles. Prove that the sum of the squares on one pair of opposite sides is equal to the sum of the squares on the other pair.
Page 49 - The six straight lines. joining two and two the centres of the four circles which touch the sides of a triangle pass each through one of the vertices of the triangle.
Page 17 - The perpendiculars from the vertices of a triangle on the opposite sides are concurrent.
Page 36 - Compare the area of the triangle formed by joining the centres of these squares with the area of the equilateral triangle.
Page 13 - The opposite angles of a quadrilateral inscribed in a circle are together equal to two right angles, with converse.
Page 39 - If two triangles have two sides of the one equal to two sides of the...
Page 16 - Wherefore, if the ratios &c. EXERCISES. 1. Shew that the locus of the middle points of straight lines parallel to the base of a triangle and terminated by its sides is a straight line. 2. CAB, CEB are two triangles having the angle B common and the sides CA, CE equal ; if BAE be produced to D and ED be taken a third proportional to BA , AC, then the triangle BDC is similar to the triangle BAC.
Page 10 - The straight line, joining the points of bisection of two sides of a triangle, is parallel to the base.