As in aei, the perpendicular eo, cutting the base ai into two equall parts ao, and oi: And the said eo is lesse than either ao, or oi: Therefore the angle aei, is a blunt angle by the [7 e].
17. An acutangled triangle is that which hath all the angles acute. 29 d j.
Therefore
18. A perpendicular drawne from the top falleth within the figure: And contrariwise.
As in aei, the perpendicular ao falleth within as is plaine by the [4 e].
And
19. If any one angle of triangle be lesse then the other two, it is acute: And contrariwise.
As is manifest by the [6 e].