Look at each triangle below and, based on the given information, decide whether you could use the Law of Sines, the Law of Cosines (or neither)
Answer
Triangle 1 and 2 are clear candidates for the law of sines
Triangle 1 (top left) - Law of Sines
Triangle 2 (Top Left)
Triangle 3( Bottom Left)
To get the measure of x . You wold first need to use the law of cosines to get the length of the side opposite the 115° triangle. From there you could use the law of sines
Triangle 4( Bottom Right)
Since the sum of the measure of the interior angles of a triangle is 180°, you can find the measure of the 3rd angle . From there you could use the law of sines to calculate the length of side x.
Decide which formula (law of Sines/Cosines) you would use to calculate the value of x below? After you decide that, try to set up the equation(Do not solve--just substitute into the proper formula)
Answer
Since you know 3 sides, and are trying to find an angle this is Law of Cosines problem.
8² = 5² + 6² -2(5)(6)(cos(x))
Decide which formula (law of Sines/Cosines) you would use to calculate the value of x below? After you decide that, try to set up the equation(Do not solve--just substitute into the proper formula)
Answer
Since you know 2 sides , their included angle, and you are trying to find the side length opposite the angle, this is Law of Cosines problem.
x
² = 11² + 7² -2(11)(7)(cos(50))
Decide which formula (law of Sines/Cosines) you would use to calculate the value of x below? After you decide that, try to set up the equation(Do not solve--just substitute into the proper formula)
Answer
Since you know a side length (11) and its opposite angle (50) and want to the angle measurement opposite the length of side 7, this is a law of sines problem
Worksheet on law of sines and law of cosines (pdf)
Graphing Calc
