Learn how to solve using the law of cosines

The video tutorial explains how to solve a triangle problem using the Law of Cosines and the Law of Sines. It begins with setting up the problem by identifying the side lengths and then proceeds to calculate the largest angle using the Law of Cosines. After determining angle C, the tutorial demonstrates how to find the other angles using the Law of Sines and the angle sum property of triangles. The process is summarized with emphasis on the importance of calculating the largest angle first.

Why can't the Law of Sines be used directly in this problem?

• Because the side lengths are not proportional.

• Because we do not have any angle measures.

• Because the triangle is not isosceles.

• Because the triangle is not a right triangle.

What is the formula for the cosine of angle C using the Law of Cosines?

• cos(C) = (a^2 + b^2 + c^2) / (2ab)

• cos(C) = (a^2 - b^2 + c^2) / (2bc)

• cos(C) = (a^2 + b^2 - c^2) / (2ab)

• cos(C) = (b^2 + c^2 - a^2) / (2ac)

What is the calculated value of angle C using the Law of Cosines?

• 120 degrees

• 105.63 degrees

• 60 degrees

• 90 degrees

What issue might arise when calculating the inverse cosine of a negative number?

• The result will be a positive number.

• The calculator might display an error.

• The result will always be zero.

• The result will be a complex number.

How is the Law of Sines used to find angle A?

• By using the ratio of side A to the cosine of angle A.

• By using the ratio of side C to the sine of angle C.

• By using the ratio of side A to the sine of angle A.

• By using the ratio of side B to the sine of angle B.

What is the sum of all angles in a triangle?

• 270 degrees

• 90 degrees

• 360 degrees

• 180 degrees

What is the final step to find the missing angle B?

• Subtract the sum of angles A and C from 180 degrees.

• Add angles A and C.

• Multiply angles A and C.

• Divide the sum of angles A and C by 2.