Principles of Plane Geometry

acute angle adjacent angles angle formed angle inscribed angle opposite angles are equal arcs intercepted base and altitude bisector Book centre chords subtending circumscribed circle Complementary angles construct a square construct a triangle construct the triangle COROLLARY diagonals diameter distance dividing a line double the number equal arcs equal circles equilateral polygon equilateral triangle equivalent exterior angles four quantities geometry given circle given line given point given square given triangle homologous sides hypotenuse Illustration included angle inscribed angle inscribed circle line bisecting line drawn line joining lines is equal median middle point number of sides oblique lines opposite angles opposite side parallel lines perimeter perpendicular PLANE GEOMETRY point equally distant Problem Proposition XVIII quadrilateral radius ratio regular polygon right angles right triangle SCHOLIUM segments similar polygons straight line supplementary angles SUPPLEMENTARY PROPOSITIONS tangent Theorem third side trapezoid triangle in terms triangles are equal variable vertex