The base angles of an isosceles triangle are the two angles that are equal to each other. They can be between 89.999...o and 0.000000..01o.
The base angles of an isosceles triangle are congruent. The vertex angle of an isosceles triangle is not necessarily congruent to the base angles.
Vertex angle
-- An isosceles triangle has two equal sides. -- An isosceles triangle has two equal angles. -- An isosceles triangle has two equal interior-angle bisectors. -- The bisector of the vertex angle of an isosceles triangle is also the perpendicular bisector of the triangle's base.
The base
The two "base" angles.
The base angles of an isosceles triangle are congruent. The vertex angle of an isosceles triangle is not necessarily congruent to the base angles.
The third angle of an isosceles triangle doesn't have a name.
Vertex angle
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-- An isosceles triangle has two equal sides. -- An isosceles triangle has two equal angles. -- An isosceles triangle has two equal interior-angle bisectors. -- The bisector of the vertex angle of an isosceles triangle is also the perpendicular bisector of the triangle's base.
No. It need not be the base angles that are equal, it can be one of the base angles and the top angle (if the triangle is tipped over). Also, the base angle are equal in an equilateral triangle - although an equilateral triangle is a special kind of isosceles triangle.
The base
The two "base" angles.
In an isosceles triangle, the altitude from the vertex angle to the base bisects the base and is also the median, as it divides the triangle into two congruent right triangles. This altitude is perpendicular to the base, creating two equal segments. Consequently, in an isosceles triangle, the altitude, median, and angle bisector from the vertex angle to the base are all the same line segment.
For an isosceles triangle with vertex 46 degrees, the sum of the remaining two base angles is 180-46 = 134 degrees. Base angles are equal because it's isosceles, so each angle is half of their sum. 134/2 = 67 degrees. Thus, any isosceles trapezoid formed inside that isosceles triangle by drawing parallel lines to the triangle's base, will have base angle measures of 67 degrees, which are triangle's base angles.
bob
To find the equal angels, base angles, of an isosceles triangle and you know the vertex angle, 180-vertex angle and then divide by two.