VIDEO PRACTICE: Law of Cosines Quiz

Why might you need to use the Law of Cosines instead of the Law of Sines?

• When you have two sides and the included angle

• When you have a right triangle

• When you have an equilateral triangle

• When you have an isosceles triangle

In which scenario is the Law of Cosines necessary?

• When you have two angles and one side

• When you have all three sides

• When you have one angle and one side

• When you have two angles and two sides

What information is given in the first case where the Law of Cosines is used?

• All three angles

• Two angles and one side

• One side and one angle

• Two sides and the included angle

What is the second case where the Law of Cosines must be used?

• When given two sides and one angle

• When given one angle and one side

• When given all three sides

• When given two angles and one side

What is the length of side C in the example problem?

• 9 units

• Unknown

• 12 units

• 50 units

What is the angle between the two given sides in the example problem?

• 30 degrees

• 45 degrees

• 50 degrees

• 60 degrees

Which formula is used to find the missing side B in the example problem?

• B^2 = a^2 + b^2 - 2ab * cos(B)

• B^2 = a^2 + b^2 - 2ab * cos(C)

• B^2 = a^2 + c^2 - 2ac * cos(B)

• B^2 = b^2 + c^2 - 2bc * cos(A)

What is the value of B squared after plugging in the given values?

• 81

• 86.1579

• 138.8421

• 225

What is the final length of side B after taking the square root?

• 9.3 units

• 12 units

• 9 units

• 50 units

What method can be used to solve the rest of the triangle after finding side B?

• Pythagorean Theorem

• Law of Sines

• Law of Cosines

• Trigonometric Ratios