Warm-up Determine the measure of the missing angle, theta in the obtuse triangle below. 2.7 3.0 46o
Homework Issues??? (page 163 # 2, 3; page 170 # 5, 7, 10, 12 - 14)
The of the Sine Law
By definition, the word ambiguous means open to two or more interpretations. Such is the case for certain solutions when working with the Law of Sines. If you are given two angles and a side opposite (ASA or AAS), the Law of Sines will nicely provide you with ONE solution for a missing side. Unfortunately, the Law of Sines has a problem dealing with SSA. If you are given information about two sides and one angle which is not contained, with no diagram, there could be zero, one, or two possible triangles that could be drawn.
For Example: In triangle ABC, angle A = 30 degrees, b = 5 and a = 3. Determine the length of c.
How can we determine how many possible triangles there are based on a particular situation??? We can always start be determining the height of the triangle.
height of triangle C A B B'
a < b sinA, there is no solution a = b sinA, there is ONE solution So, if: a < b sinA, there is no solution a = b sinA, there is ONE solution a > b sinA, there are TWO solutions a > b, there is ONE triangle only. height of triangle Note: a is the side opposite the angle. C A B b a a<bsinA = no triangle a=bsinA = one rt < triangle a>bsinA = two possible triangles
http://jwilson. coe. uga. edu/EMT668/EMAT6680 http://jwilson.coe.uga.edu/EMT668/EMAT6680.2001/Mealor/EMAT%206700/law%20of%20sines/Law%20of%20Sines%20ambiguous%20case/lawofsinesambiguouscase.html
In triangle ABC, angle A = 47 degrees, b = 10 cm In triangle ABC, angle A = 47 degrees, b = 10 cm. Find possible values of side "a" that would result in .... a) no triangles b) 1 right triangle c) 2 triangles d) 1 obtuse triangle.
Textbook Questions: Pages 183 - 185 # 4, 5, 6, 7, 9, 11 *Due tomorrow!
In triangle ABC angle A = 50 degrees, side b = 14 cm and side a = 12 cm. Calculate the measures of angles B and C.
Example 1: In triangle ABC, <A = 42o, a = 7. 2cm and b = 8. 5cm Example 1: In triangle ABC, <A = 42o, a = 7.2cm and b = 8.5cm. Find <B and <C.
C 15m 12m 120o B A