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Objectives:
-Solve oblique triangles using Law of Sines and Law of Cosines
-Find areas of oblique triangles.
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-Triangles that are not right triangles
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When the 3 measurements provided fit one of
these cases:
* Two angles and a nonincluded side (AAS)
* Two angles and the included side (ASA)
* Two sides and the included angle (SSA)
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*choose any 2 ratios to create a proportion
with 3 known measurements, and 1 unknown.
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A) Solve ΔLMN. Round side lengths to the nearest
tenth and angle measures to the nearest degree.
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B) Solve for y in ΔXYZ. Round side lengths to the
nearest tenth.
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A) The angle of elevation from the top of a
building to a hot air balloon is 62º. The angle of
elevation to the hot air balloon from the top of a
second building that is 650 feet due east is 49º.
Find the distance from the hot air balloon to
each building.
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B) A tree is leaning 10° past vertical as shown in
the figure. A wire that makes a 42° angle with
the ground 10 feet from the base of the tree is
attached to the top of the tree. How tall is the
tree?
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You know that the measures of two sides and a
nonincluded angle (SSA) do not necessarily
define a unique triangle. Consider the angle and
side measures given in the figures below.
In general, given an SSA case, one of the following
will be true:
* No triangle exists (no solution)
* Exactly 1 triangle exists (one solution)
* Two triangles exist (two solutions)
SSA
It is possible for more than 1 triangle to exist,
or NO triangle to exist. It all depends on if the
given angle is acute or obtuse.
Always look for 2 triangles when finding an
angle using Law of Sines.
https://www.youtube.com/watch?v=Io3xZMO
rbkQ
video
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Given an Obtuse 
*if OPP  ADJ, then NO ∆ exists
*if OPP > ADJ, then ONE ∆ exists
Given an Acute 
*if ADJsin() > OPP, then NO ∆ exists
*if ADJsin() = OPP, then ONE ∆ exists
*if OPP > ADJ, then ONE ∆ exists
*if ADJsin() < OPP < ADJ, then TWO ∆s exist
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1. Using the FIRST angle you found, subtract this number
from 180º. This is the 2nd degree measure for the same
angle.
2. The ORIGINAL angle given in the problem, will never
change, so take this angle AND the angle from step 1 and
subtract them from 180º. (Since all 3 angles have to add
up to 180º.)
3. Use Law of Sines with your new angles to find the
remaining side.
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A) Find all solutions for the given triangle, if
possible. If no solution exists, write no solution.
Round side lengths to the nearest tenth and
angle measures to the nearest degree.
mA = 63°, a = 18, b = 25
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B) Find all solutions for the given triangle, if
possible. If no solution exists, write no solution.
Round side lengths to the nearest tenth and
angle measures to the nearest degree.
mC = 105°, b = 55, c = 73,
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A) Find all solutions for the given triangle, if
possible. If no solution exists, write no solution.
Round side lengths to the nearest tenth and
angle measures to the nearest degree.
mB = 45°, b = 18, and c = 24.
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B) Find all solutions for the given triangle, if
possible. If no solution exists, write no solution.
Round side lengths to the nearest tenth and
angle measures to the nearest degree.
mC = 24°, c = 13, and a = 15.
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When the 3 measurements provided fit one of
these cases:
* Three sides (SSS)
* Two sides and the included angle (SAS)
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A) A triangular area of lawn has a sprinkler
located at each vertex. If the sides of the lawn
are a = 19 feet, b = 24.3 feet, and c = 21.8 feet,
what angle of sweep should each sprinkler be set
to cover?
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B) A triangular lot has sides of 120 feet, 186
feet, and 147 feet. Find the angle across from
the shortest side.
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*In SSS, you must find the LARGEST angle first,
then use the Law of Sines to find the SMALLER of the
2 remaining angles.
*In SAS, you must first find the side across from the
known angle,
then use the Law of Sines to find the SMALLER of the
2 remaining angles.
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A) Solve ΔABC. Round side lengths to the nearest
tenth and angle measures to the nearest degree.
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B) Solve ΔMNP if mM = 54o, n = 17, and p = 12.
Round side lengths to the nearest tenth and
angle measures to the nearest degree.
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C) Solve ΔABC. Round angle measures to the
nearest degree.
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*Use for SSS*
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A) Find the area of ΔABC to the nearest tenth.
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B) Find the area of ΔGHJ to the nearest tenth.
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A) Find the area of ΔABC to the nearest tenth.
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B) Find the area of ΔDEF to the nearest tenth.