Geometry Basics Chapter 1-2 Flashcards
Altitude to a side of a triangle
A segment from a vertex perpendicular to the opposite side
How many lines can be drawn through any two points?
One and only one
AB is the only line that can be drawn between A and B
Right Angle
An angle that measures 90 degrees
Right Triangle
A triangle having a right angle
Postulate 9: Powers Postulate
Like powers of equals are equal.
If a=b then a squared=b squared
Principle of Pairs of Angles: If angle of c degree is cut into two adjacent angles of a degree and b degree…
then a degree+b degree=c degree
Principle of Pairs of Angles
Hypotenuse
The longest side of a triangle
How many bisectors are in an angle?
One and only one
Only AD is the bisector of angle A
True/False: A geometric figure can be moved without change in size or shape?
True
If a Line Segment is divided into two equal parts
The point of division is the midpoint of the line segment
The line that crosses at the midpoint is said to bisect the segment
Complementary Angles
Complementary Angles are two angles whose measure total 90 degrees
If a line segment is divided into parts
The length of the whole line segment equals the sum of the length of its parts.
The length of the whole line segment is greater than the length of any part
Perpendicular
Lines, rays, or segments that meet at right angles.
Isosceles Triangle
A triangle having at least two congruent sides
The equal sides are called the legs
The remaining side is called the base
Angles on either side of the base are base angles
Angle opposite the base is the vertex angle
Postulate 4: Reflexive Postulate or Identity Postulate
Any quantity equals itself
X=X, AB=AB, angle A=angle A
Angle
An angle is the figure formed by two rays with a common end point. The rays are the sides of the angle, while the end point is its vertex.
Postulate 2: Substitution Postulate
A quantity may be substituted for its equal in any expression or equation.
If x=5 and y=x+3, we may substitute 5 for x and find y=5+3=8
Scalene Triangle
A triangle having no congruent sides
Central Angle
An angle formed by two radii
All Vertical angles
Are Congruent
Chord
A segment joining any two points on a circle
Point
Point has position only. It has no length, width, or thickness. A point is represented by a dot. A point is designated by a capital letter next to the dot.
Postulate 13: The length of a segment is the…
Shortest distance between two points
AB is shorter than the curved or broken line segment between A and B
Theorem
A statement, which when proved, can be used to prove other statements or derive other results. Each basic theorems requires the use of definitions and postulates for its proof.
Radius
A segment joining the center of a circle to a point on the circle.
The def of a circle, it follows that the radii of a circle are congruent.
Postulate 16: How many midpoints are on a given segment?
One and only one
Quadrilateral
A polygon having four sides
Postulate 14: How many circles can be drawn with any given point as center and a given line segment as a radius?
one and only one circle
only circle A can be drawn with A as center and AB as a radius
Adjacent Angles
Two angles that share the same vertex and have a common side between them.
Altitudes of obtuse triangle
Altitude drawn to either side of the obtuse angle fall outside the triangle
Thus in obtuse triangle ABC (shaded), altitudes BD and CE fall outside the triangle. In each case, a side of the obtuse angle must be extended
Plane Surface
A plane surface is a surface such that a straight line connecting any two of its points lies entirely in it. A plane is a flat surface.
Angle Bisector of a triangle
A segment or ray that bisects an angle and extends to the opposite side
BD the angle bisector of angle B, Bisects angle B making angles 1 and 2 congruent.
Median of a Triangle
A segment from a vertex to the midpoint of the opposite side
BM, the median to AC, bisects AC, making AM=MC