HolcombMath

Friday, April 17, 2009

Geometry (Class 70)

Announcements
Test Friday focusing on completing the square, special right triangles, and using right triangles.

Lesson Title
Right Triangle Ratios (1)

Overview
Students will begin the class working problems which require the application of concepts and skills related to special right triangles. The lesson for the today, “Triangle Magic”, sets the stage for our work with the relationships between the angle measures and the side lengths of right triangles. During the last part of the class students will be taking a test focusing on special right triangles, solving quadratics by completing the square, and applications of similar triangles.
Textbook Sections

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.
If triangles are similar, then the ratios of corresponding sides are equal.
If you know that two triangles are both right triangles, and you know the measure of one more angle of each of these triangles, then you can determine if the triangles are simialr.
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.
I can use the ratio of the adjacent side to the hypotenuse of a right triangle to predict the measure of the included angle.
Turn-In (#69)
Special Right Triangle Problems (Worksheet “p.365”) Written Exercises #1-20

Handouts
No Handouts Posted

Assignment
Special Right Triangle Problems (Worksheet “p.365”) Written Exercises #21-33
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.