Understanding the Law of Cosines

What is the basic formula for the Law of Cosines?

• a^2 = b^2 - c^2 + 2bc cos(A)

• a^2 = b^2 + c^2 + 2bc cos(A)

• a^2 = b^2 + c^2 - 2bc cos(A)

• a^2 = b^2 + c^2 - 2bc sin(A)

In the SSS example, what is the value of side A?

• 30

• 50

• 20

• 40

What is the first step in solving for angle B using the Law of Cosines?

• Add the squares of sides A and C

• Divide the sum of squares by the cosine of angle B

• Multiply the cosine of angle B by the product of sides A and C

• Subtract the product of sides A and C from the sum of squares

What is the approximate measure of angle B in the SSS example?

• 90 degrees

• 104 degrees

• 120 degrees

• 150 degrees

In the SAS example, what is the given angle C?

• 40 degrees

• 30 degrees

• 60 degrees

• 50 degrees

What is the formula used to find side C in the SAS example?

• C^2 = A^2 + B^2 - 2AB sin(C)

• C^2 = A^2 - B^2 + 2AB cos(C)

• C^2 = A^2 + B^2 + 2AB cos(C)

• C^2 = A^2 + B^2 - 2AB cos(C)

What is the approximate length of side C in the SAS example?

• 12 units

• 13 units

• 10 units

• 15 units

Can the Law of Cosines be used to find other angles in a triangle?

• No, it can only be used for one angle

• Yes, it can be used for any angle

• Yes, but only for right triangles

• No, it is only for finding sides

What is the significance of a negative cosine value in the context of angles?

• The angle is reflex

• The angle is obtuse

• The angle is acute

• The angle is right

What should you do if your teacher asks you to round off the angle measurement?

• Round to the nearest tenth

• Round to the nearest hundredth

• Do not round

• Round to the nearest whole number