This document discusses key concepts related to similarity in geometry, including definitions of similar figures, scale factors, and different methods of proving similarity between triangles. It introduces several similarity transformations, such as dilations, translations, and rotations. Examples are provided to illustrate proportional side lengths and equal angles as properties of similar figures.
3. Choose 3-4 vocabulary words for the day. Throughout the lesson, as students
respond to your questions or are presenting a problem on the board, mark a tally
when a vocabulary word is used accurately. This can be turned into a competition
among groups or between periods.
Mathematically Speaking!
Examples of accuracy
line vs line segment
translation vs slide
midpoint vs the middle
4. Betweenness given three points A, B, and
C, B is between A and C if and only if all
three of the points lie on the same line, and
AB + BC = AC.
A C
B
6. Scale factor in a dilation, the ratio of a
linear measurement of the image to the
corresponding measurement of the
preimage.
Scale Factor =
9
3
= 3
7. Similar Figures figures with the same shape (but not
necessarily the same size) and the following properties:
Corresponding sides are proportional. That is, the
ratios of the corresponding sides are equal.
Corresponding angles are equal.
8. Similarity transformation
a transformation that
results in an image that is
the same shape, but not
necessarily the same size,
as the original figure.
9. Dilation a transformation in
which the lines connecting every
point with its preimage all
intersect at a point known as
the center of dilation, and
咋
咋
is
the same for every point ; a
transformation that changes the
size of a figure but not its shape.
G
10. Side-Side-Side similarity if the
corresponding side lengths of two triangles
are proportional, then the triangles are
similar.
11. Side-Angle-Side similarity if the lengths of
two pairs of corresponding sides of two
triangles are proportional and the angles
the sides form are congruent, then the
triangles are similar.
12. Angle-Angle similarity If two angles of
one triangle are respectively equal to
two angles of another triangle, then the
two triangles are similar.
13. Side Splitter Theorem If a line is parallel to a
side of a triangle and intersect the other two
sides, then this line divides those two sides
proportionally.
=
=
瑞