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Chapter 4 Notecards

Triangle A closed figure consisting of three line segments linked end-to-end.
Scalene Triangle A triangle with all sides of different lengths.No sides are equal and no angles are equal
Isosceles Triangle A triangle with two equal sides The angles opposite the equal sides are also equal
Equilateral Triangle A triangle with all three sides of equal length.All the angles will be 60°
Acute Triangle A triangle that has all angles less than 90°
Right Triangle A triangle that has a right angle (90°)
Obtuse Triangle A triangle that has an angle greater than 90°
Equiangular Triangle A triangle with all angles equal (60°). The same as an Equilateral Triangle
Interior Angles Any of the four angles formed between two straight lines intersected by a third straight line. The angle formed inside a polygon by two adjacent sides.
Exterior Angles The Exterior Angle is the angle between any side of a shape, and a line extended from the next side.
Triangle Sum Theorem The sum of the interior angles of any triangle is equal to 180 degrees.
Exterior Angle Theorem The measure of an exterior angle of a triangle is equal to the sum of the measures of the two non-adjacent interior angles of the triangle.
Corollary to a theorem A Corollary is a theorem that follows on from another theorem
Corollary to the Triangle Sum Theorem According to triangle sum theorem the sum of three angles of triangle is always to 180 degree. There is no triangle having two angles of 90 degree. So, it means if you have two angles of triangle than you can find the third angle.
Congruent Figures Two shapes are congruent if you can Turn, Flip and/or Slide one so it fits exactly on the other.
Corresponding Parts the angle sides and vertices that are in the same location in congruen figures
Third Angles Theorem if two angles of one triangle are congrurent to two angles of another triangle the the third angle are also congruent
Reflexive property of congruent triangles WAX=abc then abc=WAx
symmetric property of congruent triangles Triangles are congruent when all corresponding sides and interior angles are congruent. The triangles will have the same shape and size, but one may be a mirror image of the other.
Transitive property of congruent triangles f a = b and b = c, then a = c, right? That’s transitivity. And if a = b and b < c, then a < c. That’s substitution. Easy enough. Below, you see these theorems in greater detail:
Side – Side – Side Congruence Postulate (SSS) Triangles are congruent if all three sides in one triangle are congruent to the corresponding sides in the other.
Side – Angle – Side Congruence Postulate (SAS) Triangles are congruent if any pair of corresponding sides and their included angles are equal in both triangles.
Legs of a right triangle In a right triangle, the sides opposite to the acute angles are called the Legs of a Triangle.
Hypotenuse The side opposite the right angle in a right-angled triangle
Hypotenuse – Leg Congruence Theorem (HL Two right triangles are congruent if the hypotenuse and one corresponding leg are equal in both triangles.
Created by: theleagen