Using law of cosines to find our missing length of a triangle

The video tutorial explains how to solve a triangle problem using the law of cosines. It begins by introducing the problem and the given values of the triangle. The instructor then discusses the decision-making process between using the law of sines or cosines, ultimately choosing the latter due to the available information. The tutorial proceeds with a step-by-step application of the law of cosines, including detailed calculations, to find the length of side a. The video concludes with the final result of the calculation.

What are the given values for the triangle ABC in the problem?

• Angle A = 30 degrees, side b = 15.4, side c = 9.7

• Angle A = 45 degrees, side b = 10.4, side c = 7.7

• Angle A = 60 degrees, side b = 11.4, side c = 6.7

• Angle A = 23 degrees, side b = 12.4, side c = 8.7

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

• Because the sides are not in proportion

• Because there is no angle-side pair available

• Because the triangle is not a right triangle

• Because the angles are not given in radians

Which law is used to solve for side 'a' in this problem?

• Law of Cosines

• Law of Tangents

• Pythagorean Theorem

• Law of Sines

What is the formula used to calculate side 'a' using the Law of Cosines?

• a^2 = b^2 + c^2 - 2bc sin(A)

• a^2 = b^2 + c^2 + 2bc sin(A)

• a^2 = b^2 + c^2 - 2bc cos(A)

• a^2 = b^2 - c^2 + 2bc tan(A)

What is the calculated length of side 'a'?

• 4.55

• 5.55

• 6.55

• 7.55