2-8 Proportions and Similar Figures

2-8 Proportions and
Similar Figures
Similar Figures: Have the same shape
but not necessarily the same size
The measures of corresponding angles
are equal, and corresponding side
lengths are proportional
The order of the letters when you
name the figures is so important
because it tells you which parts of the
figure are corresponding parts
Problem 1: Finding the Length
of a Side
Problem 2: Applying Similarity
The sun’s rays strike the building and the girl at the
same angle, forming two similar triangles shown.
How tall is the building
Scale drawing: a drawing that is similar to
an actual object or place
(floor plans, blueprints, maps)
Scale: the ratio of any length on the
drawing to the actual length
Problem 3: Interpreting Scale
What is the actual distance from
Jacksonville to Orlando?
Scale Model: a three-dimensional
model that is similar to a threedimensional object
Problem 4: Using Scale Models
A giant model heart is shown below. The heart is the
ideal size for a man who is 170 ft. tall. About what
size would you expect the heart of the man who is 6
ft. tall to be?