Wednesday, May 21, 2008
Geometry (Class 83)
Announcements
Test Next Class-- Covers Chapter 10.
Lesson Title
Law of Sines
Overview
Our warm-up for today takes us back to right triangle trigonometry. The problem requires students to analyze a diagram, find right triangles, and then use right triangle trigonometry to solve a number of sub-problems in order to arrive at a final solution. The lesson for today marks the start of learning how to deal with triangles which do not have a right angle. In particular we see how what we learned about the relationships between the arcs, angles, and segment lengths of circles can give us a very important tool— the Law of Signs (applause, peals of thunder…)!
Textbook Sections
Supplementary
Vocabulary
center
inscribed angle
central angle
radius (pl: radii)
chord
diameter
sections of intersecting chords
extended chords
inscribe
cyclic quadrilateral
Key Attitudes
Math is about thinking creatively.
Key Ideas
The Law of Sines is a consequence of relationships between arcs and angles of circles.
Th eLaw of Sines can be sued to find missing side lengths or angle measures of triangle including those which are not right triangles.
THe Law of Sines is a proportion stating that the ratio of the side length and the sine of the opposite angle is the same for all side/opposite angle pairs in any triangle.
Key Skills
I can use right triangle trigonometry to solve a problem.
I can show how the Law of Sines is a consequence of the relationships between arcs, angles, and segment lengths in a circle.
I can use the Law of Sines to solve for missing length sides and angles in a triangle.
I can recognize a situation where using the Law of Sines would be useful.
I can translate a situation into an equation involving the Law of Sines and solve that equation.
Turn-In (#82)
Benchmark Test 2-- Skip #30c and just write the proof for #36 if the flow chart confuses more than helps.
Finish Warm-Up
Handouts
Chapter 13- Lesson 1: Warm-Up
Chapter 13- Lesson 1: Law of Sines
Chapter 13- Lesson 1: Law of Sines- Problems
Assignment
Txt. p. 650 Chapter 10 Review #1-23
Txt. p.653 #2-19 (Optional)
Complete Chapter 10 Outline
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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