Starter MondayApril , 2015
a5
cA 51°
84°
𝒂sin 𝑨
=𝒃
sin𝑩=
𝒄sin𝑪
1. Use the Law of Sines to calculate side c of the triangle.
2. Find the measure of angle A.
Test Revisions• Overall goal: YOU learning new concepts and problem-
solving skills• Test goal: To see what you have learned, what you are still
learning, and to provide MULTIPLE opportunities to show mastery
1. Today, we will review the FIRST test answers together – take notes!
2. You will have until next class to study3. Next class, you will retake ONLY the questions you missed on
a NEW test4. Next class, you will turn in BOTH the NEW test AND the
FIRST test5. You need to retake questions if you have a 10 or less. A score
of 10/14 is 71.4 percent, which is a C-.
• If you haven’t taken the test yet:1. Take notes today2. Next class, you will take the NEW test
Objectives1. Use the Law of Sines to solve for the sides and angles of
ANY triangle.2. Use the Law of Cosines to solve for the sides and angles
of ANY triangle.3. Use sine to find the Area of a Triangle.
Area of a Triangle
*Use this equation for area WHEN we know two (2) sides AND the angle between them (SAS).
ab
cA B
C
EITHER
OR
OR
Area of a Triangle
*Use this equation for area WHEN we know two (2) sides AND the angle between them (SAS).
a10
725° B
C
EITHER
OR
OR
Area of a Triangle
*Use this equation for area WHEN we know two (2) sides AND the angle between them (SAS).
231 m150 m
cA B
123°
EITHER
OR
OR
Law of Cosines
𝑐2=𝑎2+𝑏2−2∗𝑎∗𝑏∗ cos𝐶• a, b, and c are sides• A, B, and C are angles
• Side a faces angle A; side b faces angle B; side c faces angle C
• Use Law of Cosines to find:• The third side of a
triangle when we know two sides and the angle between them; or
• The angles of a triangle when we know all three sides
ab
cA B
C
Law of Cosines
𝑐2=𝑎2+𝑏2−2∗𝑎∗𝑏∗ cos𝐶• a, b, and c are sides• A, B, and C are angles
• Side a faces angle A; side b faces angle B; side c faces angle C
• Calculate side c
811
cA B
37°
Law of Cosines
𝑐2=𝑎2+𝑏2−2∗𝑎∗𝑏∗ cos𝐶• a, b, and c are sides• A, B, and C are angles
• Side a faces angle A; side b faces angle B; side c faces angle C
• Calculate angle C
86
7A B
C
Law of Cosines• a, b, and c are sides• A, B, and C are angles
• Side a faces angle A; side b faces angle B; side c faces angle C
• Use Law of Cosines to find:• The third side of a
triangle when we know two sides and the angle between them
• The angles of a triangle when we know all three sides
ab
cA B
C
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