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Practice exam: correctionsModeling fractions (on board)
Continue CIRCLES
New topic: SIMILARITY
Agenda for today
An obstacle”A measure of effort or participation during
class”Stressful (they put pressure on you)”(usually) too long”Full of confusing questions (wording is
confusing)”Just another piece of paper”No problem (if everything has been
covered and it’s not too long)”
"Tests are…
Kid Cudi – Super BooGodsmack – ToucheHillbilly NinjaInvisible String – Stopping Cars
Tunes
To find a part (arc, L)of the circumference:
Circles (continued)
To find the area ofa sector:
Circles (continued)
Find the arc spanned by the Pacific Crest Trail
Clues:17o of latitudeEarth’s diameter:
12,742 km
http://upload.wikimedia.org/wikipedia/commons/0/02/Pacific_crest_trail_route_overview.png
Circles (continued)
Find area of whole, area of a sector
Find circumference, arc length
Find radius, diameter
Apply vocabulary
FIRST, SECOND, THIRD PROBLEM SETS(from the Day Five Assignment)
Circles TASKS
http://www.youtube.com/watch?v=HEheh1BH34Q&feature=related
http://www.youtube.com/watch?v=OuC8hOC_wO0
When you see a really accurate drawing, it is a shape
similar to the original
EXAMPLES ON BOARD
Topic: Similar polygons
Discussion questionsBeef or chicken?Is there a consistent relationship between
area and its perimeter (for each polygon)?When do I call it a fraction and when a
ratio?What does proportion mean?What is the difference between a ratio and
a percent?
Similar polygons (cont'd)
If two polygons are similar…
They have the same angle sizes in the same order
ANDThey have corresponding sides whose ratios are equal
FOURTH PROBLEM SET
Similar polygons (continued)
Scale drawings have a scale that shows the ratio of the scale drawing to the real size
What is the width of the real version of this house?
Similar polygons (cont'd)
Lighthouse – how tall is the real thing if the scale of this model is 1:1200?
Elephant – how tall is the real thing if the scale of this model is 1:120?
Car – come up with the scale based on the actual length of Dodge’s 2005 Charger: 200 inches
Ship’s cannon – come up with the scale based on an actual barrel length of 5 feet
Beaver – If the actual length of Castor canadensis is 2 feet from snout to tip of tail and model length is 2 inches, what is the scale?
Quarters – when the case is open, what is the ratio of area of paper to area of quarters?
Eyeballs – if real human eyes are 1 inch in diameter, what is the scale of the chocolate eyeball model?
Green plastic design tool – draw (and furnish) a room and label the scale factor
Bicycle map – based on the map’s scale, what is the closest that the Willamette River gets to Rocky Butte (as the paper airplane flies)
More…
Triangles are similar if they…
Have the same angle sizes in the same order (AA)
Have corresponding sides whose ratios are equal (SSS)
Have two corresponding sides with the same angle between them (SAS)
Similar polygons (con't)
Draw similar polygons
Create a scale drawing
Determine whether two polygons are similar or not
FIFTH & SIXTH PROBLEM SETS
Similar polygonsTASKS
What is the relationship between the size of individual triangles’ interior angles and the sides across from them?
Discussion question