Points, Lines and Planes The most basic figures of geometry
Point - an exact location. A
point A
It has no size at all, but is usually represented as a dot. Use a capital letter to name a point
Line - a straight path that extends without end in opposite directions. X
n
Y
Use two points on the line or a lowercase letter to name a line
Plane - a perfectly flat surface that extends infinitely in all directions Use three points in any order, not on the same line, to name a plane plane ABC
Identifying Points, Lines and Planes
Identifying Points, Lines and Planes
Identifying Points, Lines and Planes
Line Segments and Rays ray - a part of a line.
It has one endpoint and extends without end in one direction. Name the endpoint first when naming a ray.
Line segment- a part of a line or a ray that extends from one endpoint to another Use the endpoints in any order to name a line segment
Naming geometric figures
Congruent- figures that have the same shape and size Line segments are congruent if they have the same length. Use tick marks to indicate congruent line segments.
Guided Practice https://drive.google.com/open?id=0B38vJgVzMYKNakZsWnFIeXl0YXc
Individual Practice p. 444 1-12
https://www.ixl.com/math/grade-7 X.1Lines, line segments, and rays
Part II
Classifying Angles
angle • a figure formed by two rays that have the same initial point (The shared initial point is called the vertex.)
degrees •units used to measure angles (fraction of a circle)
CLASSIFICATIONS OF ANGLES
ACUTE •measures o between 0 o and 90
RIGHT •measures EXACTLY o 90
OBTUSE •measures o between 90 o and 180
STRAIGHT •measures EXACTLY 180
o
NAMING ANGLES
#1 BY THE VERTEX C A
1
T
∠ A
#2 BY A NUMBER ( NOT the measure ) C A
1
T
∠ 1
#3 BY 3 POINTS (vertex and 1 point on each ray)
C A
1
∠CAT or ∠TAC ***Order can be
T
reversed BUT the vertex MUST be in the middle!!!
Complementary Angles/Supplementary Angles If the sum of the measures of two angles is 90 degrees, then the angles are complementary angles. If the sum of the measures of two angles is 180 degrees, then the angles are supplementary angles.
Complementary Angles ✱ The sum of the measures of two complementary angles is
90°. < K and < M are complementary angles < K + < M = 90° Κ
Μ
Supplementary Angles ✱
The sum of the measures of two supplementary angles is 180°. < A and < B are Supplementary Angles < A + < B = 180°
Α
* A straight line = 180°
Β
Guided Practice https://drive.google.com/open?id=0B38vJgVzMYKNL Wg3SHl3dExTTnc
Independent Practice P. 450 1-21
Part III
Angle Relationships
PARALLEL LINES
*Always same distance apart, and never intersect!
PERPENDICULAR LINES
*Lines that intersect with each other to form 4 Right Angles (90°), often looks like the letter t , T
Intersecting Lines *Lines that intersect with each other through a common point *Lines that intersect form 4 angles, none of which are Right angles
IXL Practice X.2Parallel, perpendicular, intersecting
Skew Lines - do not intersect and they are not parallel. They lie in different planes.
Adjacent Angles -
Have a common vertex and a common side, but no common interior points Formed by two intersecting lines are supplementary
Vertical Angles ✱ When two lines intersect, two pairs of vertical angles
are formed. Vertical angles often look like the letter X.