-
If SSS
- Given sides a, b, and c,
Use the Law of Cosines to determine
m
A.
- Use the Law of Cosines to determine
m
B.
- Use the sum of the angles of a triangle =
180
to find
m
C.
-
If SAS
- Given sides a and b, and
C,
Use the Law of Cosines to determine side c.
- Use the Law of Cosines to determine
B.
- Use the sum of the angles of a triangle =
180
to find
m
A.
-
If ASA
- Given
m
A and
m
B
and side c,
Use the sum of the angles of a triangle =
180
to find
m
C.
- Use the Law of Sines to determine side b.
- Use the Law of Sines to determine side a.
-
If AAS
- Given
m
A and
m
B
and side a,
Use the sum of the angles of a triangle =
180
to find
m
C.
- Use the Law of Sines to determine side b.
- Use the Law of Sines to determine side c.
-
If SSA (Ambiguous Case)
- Given sides a and b, and
A,
Use the Law of Sines to solve for sin
B.
-
If sin
B > 1,
There is no triangle.
-
If sin
B
1,
Determine m
B in quadrant I.
-
If m
A +
m
B
180
There is no triangle.
-
If m
A +
m
B
< 180
There is at least one triangle.
- Determine m
B
in quadrant II.
It has the same sine value as
B .
Call this angle,
B'.
- Determine m
A
+ m
B'
- If m
A
+ m
B'
180
There is only one triangle.
- Determine m
C
using the sum of the angles in a triangle =
180
- Determine side c using the Law of Sines.
- If m
A
+ m
B'
< 180
There are two triangles.
- Determine m
C
using the sum of the angles in a triangle =
180
- Determine side c using the Law of Sines.
- Determine m
C'
using the sum of the angles in a triangle =
180
- Determine side c' using the Law of Sines.
- Given sides a, b, and c,
Use the Law of Cosines to determine mA.
- Use the Law of Cosines to determine
m
B.
- Use the sum of the angles of a triangle =
180
to find m
C.
- Given sides a and b, and
C,
Use the Law of Cosines to determine side c. - Use the Law of Cosines to determine
B.
- Use the sum of the angles of a triangle =
180
to find m
A.
- Given
m
A and m
B and side c,
Use the sum of the angles of a triangle = 180to find m
C.
- Use the Law of Sines to determine side b.
- Use the Law of Sines to determine side a.
- Given
m
A and m
B and side a,
Use the sum of the angles of a triangle = 180to find m
C.
- Use the Law of Sines to determine side b.
- Use the Law of Sines to determine side c.
- Given sides a and b, and
A,
Use the Law of Sines to solve for sinB.
-
If sin
B > 1,
There is no triangle. -
If sin
B
1,
Determine mB in quadrant I.
-
If m
A + m
B
180
There is no triangle. -
If m
A + m
B < 180
There is at least one triangle.- Determine m
B in quadrant II.
It has the same sine value asB .
Call this angle,B'.
- Determine m
A + m
B'
- If m
A + m
B'
180
There is only one triangle.
- Determine m
C using the sum of the angles in a triangle = 180
- Determine side c using the Law of Sines.
- Determine m
- If m
A + m
B' < 180
There are two triangles.
- Determine m
C using the sum of the angles in a triangle = 180
- Determine side c using the Law of Sines.
- Determine m
C' using the sum of the angles in a triangle = 180
- Determine side c' using the Law of Sines.
- Determine m
- If m
- Determine m
-
If m
-
If sin
The analysis of the Ambiguous Case was taken from a letter to The Mathematics Teacher by Carolyn J. Case, Vincennes University, Vincennes, IN.