can the base angle of an isosceles triangle be obtuse
Isosceles triangle Whether the isosceles triangle is acute, right or obtuse depends on the vertex angle. In Euclidean geometry, the base angles cannot be obtuse (greater than 90°) or right (equal to 90°) because their measures would sum to at least 180°, the total of all angles in any Euclidean triangle. Since a triangle is obtuse or right if and only if one of its angles is obtuse or right, respectively, an isosceles triangle is obtuse, right or acute if and only if its vertex angle is respectively obtuse, right or acute.
Perpendicular The legs of a right triangle are perpendicular to each other.
Isosceles triangle In an isosceles triangle that has exactly two equal sides, the equal sides are called legs and the third side is called the base. The angle included by the legs is called the vertex angle and the angles that have the base as one of their sides are called the base angles.[6] The vertex opposite the base is called the apex.[7] In the equilateral triangle case, since all sides are equal, any side can be called the base.[8]
Limit of a function (the Dirichlet function) has no limit at any x-coordinate.