4.1 Flashcards
Congruent Triangles
If triangle ABC is congruent to triangle PQR, then there is a correspondence between their angles and sides such that corresponding angles are congruent and corresponding sides are congruent
Equilateral Triangle
An equilateral triangle has three congruent sides
Isosceles Triangle
An isosceles triangle has at least two congruent sides
Scalene Triangle
A scalene triangle has no sides congruent
Acute Triangle
An acute triangle has three acute angles
Equiangular Triangle
An acute triangle that has three congruent angles
Right Triangle
A right triangle has exactly one right angle
Obtuse Triangle
An obtuse triangle has exactly one obtuse angle
Vertex
In triangle ABC, each of the points, A, B, and C is a vertex of the triangle
Opposite Side
In triangle ABC, side (segment) BC is the side opposite angle A
Adjacent Sides
In a triangle or other polygon, two side ls that share a common vertex are adjacent sides
Legs of a rt triangle
In a right triangle, the two sides that are adjacent to the right angle are the legs if the triangle
Hypotenuse
In a right triangle, the side that is opposite the right angle is the hypotenuse of the triangle
Legs of an isosceles triangle
In an isosceles triangle that has two congruent sides, the two congruent sides are called the legs.
Base of an isosceles Triangle
In an isosceles triangle that has two congruent sides, the third side not congruent to the other two is called the base.
Thm 4.1: properties of congruent triangles
- Every triangle is congruent to itself. 2. If triangle ABC is congruent to triangle PQR, then triangle PQR is congruent to triangle ABC. 3. If triangle ABC is congruent to triangle PQR, and triangle PQR is congruent to triangle TUV, then triangle ABC is congruent to triangle TUV
Interior angles
The original three angles of the triangle are the interior angles
Exterior angles
The angles that are adjacent to interior angles are the exterior angles of the triangle
Thm 4.2: triangle sum thm
The sum of the measures of the interior angles of a triangle is 180 degrees.
Thm 4.3: third angles thm
If two angles of one triangle are congruent to two angles of a second triangle, then the third angles are also congruent
Thm 4.4
The acute angles of a right triangle are complementary
Thm 4.5: exterior angles thm
The measure if an exterior angle of a triangle is equal to the sum of the measures of the two remote (nonadjacent) interior angles
Thm 4.6 exterior angles inequality thm
The measure of an exterior angle of a triangle is greater than the measure of either of the two remote (non adjacent) interior angles
