It is a consectary out of the condition of an equicrurall triangle of two, both shankes and angles, as in the example aei, shall be demonstrated.
And
20. The angle of an equilater triangle doth
countervaile two third parts of a right angle. Regio. 23. p j.
For seeing that 3. angles are equall to 2. 1. must needs be equall to 2/3.
And
21. Sixe equilater triangles doe fill a place.
As here. For 2/3. of a right angle sixe lines added together doe make 12/3. that is foure right angles; but foure right angles doe fill a place by the [27. e. iiij].
22. The greatest side of a triangle subtendeth the greatest angle; and the greatest angle is subtended of the greatest side. 19. and 18. p j.