Law of Sines and Cosines Problem
Solve for α in the oblique triangle ABC; AB = 30; AC = 15 and angle B = 20°
Oblique triangle ABC; AB = 30; AC = 15 and angle B = 20°
Type out the two equations substituting the numbers from the diagram.
Type out the Law of Sines set of relationships and type out the most appropriate
version to use the Law of Cosines for this solution.
Solve for a using both methods (show step by step work)
Sine Law:
𝐴 ?
Cosine Law:
( )( )
𝐶 ? 𝐵
( )( )
( )( )
𝐵𝐶 ?
We know that we have to find A, C and BC.
First, we are going to solve using Sine Law
We search C using:
We pass the 30 that is dividing to multiply on the other side of the equation and as
We apply the inverse of sine to clear C
( )
We calculate the approximate value
Solve for α in the oblique triangle ABC; AB = 30; AC = 15 and angle B = 20°
Oblique triangle ABC; AB = 30; AC = 15 and angle B = 20°
Type out the two equations substituting the numbers from the diagram.
Type out the Law of Sines set of relationships and type out the most appropriate
version to use the Law of Cosines for this solution.
Solve for a using both methods (show step by step work)
Sine Law:
𝐴 ?
Cosine Law:
( )( )
𝐶 ? 𝐵
( )( )
( )( )
𝐵𝐶 ?
We know that we have to find A, C and BC.
First, we are going to solve using Sine Law
We search C using:
We pass the 30 that is dividing to multiply on the other side of the equation and as
We apply the inverse of sine to clear C
( )
We calculate the approximate value
