Elements of Geometry

AB is equal AC is equal adjacent angles algebraical alternate angles angle ABC angle ACB angle AGH angle BAC angle contained angle EDF angle equal axiom base BC bisected circle definition demonstration diagonals double equal angles equal to AC equal to twice equilateral triangle Euclid Euclid's Elements exterior angle Geometrical given line given point given straight line gnomon greater hypotenuse interior and opposite isosceles triangle join Let ABC line BC line be divided linear units lines be drawn magnitude meet opposite angles opposite sides parallel straight lines parallel to BC parallelogram perpendicular porism problem produced Prop proved Q. E. D. PROPOSITION quadrilateral rectangle AC rectangle contained remaining angle right angles right-angled triangle segments shew shewn side BC square described square on AC THEOREM trapezium triangle ABC twice the rectangle unequal vertex wherefore