Wednesday, April 15, 2009
Geometry (Class 69)
Announcements
Test Friday focusing on completing the square, special right triangles, and using right triangles.
Lesson Title
Special Right Triangles (3)
Overview
The opener for today continues to focus on solving quadratic equations by completing the square and also has a few problems intended to help students review how to solve for the lengths of the sides of special right triangles. Students then will have an opportunity for more practice working with special right triangles-- first as a “Partner Challenge” and then by working a new set of problems.
Textbook Sections
§9.4 (Txt. p.551) Special Right Triangles
Vocabulary
right triangle
leg
hypotenuse
special right triangle
trigonometry
isosceles right triangle
equilateral triangle
equiangular triangle
45-45-90 triangle
30-60-90 triangle
Key Attitudes
Math is about building up understanding one idea at a time.
Key Ideas
Certain right triangles are special-- we can figure out the lengths of all three sides when we know the length of only one side.
A 30-60-90 triangle can be created by folding an equilateral triangle.
A 45-45-90 triangle can be created by folding a square.
The fact that the special right triangles are formed either as half of a square or half of an equilateral triangle provides a means to find the length of the other sides when the length of one side is known.
The Pythagorean Theorem can be used to find the length of a missing side of a right triangle when the lengths of two sides are known.
Key Skills
I can find the length of the missing two sides of a 45-45-90 right triangle when I know the length of the remaining side.
I can find the length of the missing two sides of a 30-60-90 right triangle when I know the length of the remaining side.
I can use properties of special right triangles to solve problems.
Turn-In (#68)
Txt. p.554 #12-17, 21, 22, 24
Handouts
9.1 Special Right Triangles Problems
Assignment
Special Right Triangle Problems (Worksheet “p.365”) Written Exercises #1-20
Disclaimer- The assignment as stated in class is the official assignment. Every effort is made to keep this posting accurate, but you should refer to what was stated in class as the final word.
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