## Euclid, Book 1 |

### Common terms and phrases

AC is equal adjacent angles Algebra angle ABC angle ACB angle AGH angle BAC angle EDF angle equal angle GHD Axiom base BC bisect centre circle Constr Construct a triangle contained angle depends on Prop diagonals Divide a given draw a line equal in area equal to AC equal to twice equilateral triangle Euclid exterior angle figure of Prop geometrical given angle given line given point given straight line given triangle gnomon greater hypotenuse interior opposite angle isosceles triangle join length Let the straight M.A. Lond measure middle point opposite sides parallel to BC parallelogram produced quadrilateral quadrilateral figure rectangle AB rectangle AQ rectangle contained rhombus right angles right-angled triangle side AC sides equal square on AC theorem triangle ABC triangle DEF twice the rectangle UNIVERSITY TUTORIAL SERIES vertex

### Popular passages

Page 45 - If two triangles have two angles of the one equal to two angles of the other, each to each, and one side equal to one side, viz.

Page 126 - If a straight line be bisected, and produced to any point ; the rectangle contained by the whole line thus produced, and the part of it produced, together with the square on half the line bisected, is equal to the square on the straight line which is made up of the half and the part produced.

Page 31 - If, at a point in a straight line, two other straight lines, upon the opposite sides of it, make the adjacent angles together equal to two right angles, these two straight lines shall be in one and the same straight line.

Page 138 - To divide a given straight line into two parts, so that the rectangle contained by the whole and one of the parts, shall be equal to the square on the other part.

Page 2 - A diameter of a circle is a straight line drawn through the centre, and terminated both ways by the circumference.

Page 66 - All the interior angles of any rectilineal figure, together with four right angles, are equal to twice as many right angles as the figure has sides.

Page 130 - If a straight line be divided into any two parts, four times the rectangle contained by the whole line, and one of the parts, together with the square of the other part, is equal to the square of the straight line which is made up of the whole and that part.

Page 99 - The straight line joining the middle points of two sides of a triangle is parallel to the third side and equal to half of it 46 INTERCEPTS BY PARALLEL LINES.

Page 26 - To draw a straight line at right angles to a given straight line, from a given point in the same.

Page 63 - Through a given point to draw a straight line parallel to a given straight line, Let A be the given point, and BC the given straight line : it is required to draw through the point A a straight line parallel to BC.