Transcript rttSS 1.2 Scaling Up and Down - Corresponding Sides Angles.pptx

Quick Start Expectations
1.Teaching Target:
I can compare measurements in copies with
different size factors.
2. Read over your new Learning Log HW:
1) Complete Notes on pg. 6 of SS Inv. 1 packet
by watching the Zaption Video Tour for SS 1.3
2) Math XL – 30 mins this week
3. Warm-up:
1) WHAT determines whether two shapes are similar?
2) WHAT is the same and what is different about
two similar figures?
Daphne thinks the school copier can make accurate copies in a
variety of sizes.
She makes a copy of “Super Sleuth” with the size factor set at 75%.
Then, she makes a copy with a setting of 150%.
You will compare the three figures.
First, let’s review some important vocabulary:
Copied at 75%
Original design
Vocabulary Toolkit:
Copied at 150%
The percent (%) of the enlargement
or the reduction from the original
design.
Corresponding sides have the same
relative position in similar figures.
Corresponding angles have the
same relative position in similar
figures.
Work with your table group to complete the table Inv. 1 packet
and compare the two copies to the original on LS 1.2
p. 5
75% copy
The length and perimeter of the small figure are 0.75 (or 75%) times
as long as the lengths of the original figure.
150% copy
The length and perimeter of the large figure are 1.5 times (or 150%)
as large as the lengths of the original figure.
How do the relationship in the angle comparisons relate to the copier size factors used?
The angle measure remain the same!
The area of the smallest figure is a little more
than half the area of the original .
The area of the largest figure is a little more
than double the area of the original.
The measures of the corresponding angles are
the same, but the side lengths and the area
may be different.
Each side length in the image is found by multiplying
the original length by the same number.
How about the area?
Since the sides are changed by a factor, the area
(a product of the sides: l x w) is changed by a
product of the factor and itself.
(Squares of the copier size factors!)
Reminders:
• Homework is a Zaption video on SS 1.3. Complete notes on pg. 6.
• MathXL – 30 mins this week.