13. All equilateral triangles are acute triangles. An equilateral triangle has three sides of equal length and three equal angles of 60.~ I think it is False.
14. If a triangle has two acute angles, then the third angle must also be acute.~ I think it is true.
15. A triangle cannot be right-angled and obtuse angled at the same time. Since a right-angled triangle has one right angle, the other two angles are acute. Therefore, an obtuse-angled triangle can never have a right angle; and vice versa. ~I think it is false.
