Therefore
14. If the obtuse or blunt angle be at the base of the triangle given, a perpendicular drawne from the toppe
of the triangle, shall fall without the figure: And contrarywise.
As here in aei, the perpendicular io, falleth without: This is manifest by the [4 e].
And
15. If one angle of a triangle be greater than both the other two, it is an obtuse angle: And contrariwise.
This is plaine by the [6 e].
And
16. If a right line drawne from the toppe of the triangle cutting the base into two equall parts, be lesse than one of those halfes, the angle at the toppe is a blunt-angle. And contrariwise.