Understanding the Law of Cosines

The video tutorial explains how to determine the largest angle in a triangle given the lengths of its sides. It uses the Law of Cosines to calculate the angle opposite the longest side. The process involves labeling the triangle, applying the Law of Cosines, solving the resulting equation, and using a calculator to find the angle in degrees. The tutorial also briefly mentions using the Law of Sines to find the other angles, emphasizing the sum of interior angles in a triangle is 180 degrees.

What is the largest angle in a triangle related to?

• The shortest side

• Any side

• The longest side

• The middle side

Which angle is labeled as 'A' in the triangle?

• The angle opposite side A

• Any angle

• The angle opposite side B

• The angle opposite side C

Tags

CCSS.HSG.SRT.D.10

CCSS.HSG.SRT.D.11

What is the formula for the Law of Cosines used in this problem?

• 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

Tags

CCSS.8.EE.A.2

What is the value of 26 squared?

• 529

• 100

• 676

• 460

Tags

CCSS.8.EE.A.2

What operation is performed to isolate cosine A in the equation?

• Subtraction

• Multiplication

• Addition

• Division

Tags

CCSS.4.MD.C.6

What is the approximate measure of angle A?

• 85.9 degrees

• 95.9 degrees

• 105.9 degrees

• 115.9 degrees

Tags

CCSS.HSG.SRT.C.7

Which trigonometric function is used to find angle A from cosine A?

• Sine

• Inverse Cosine

• Tangent

• Inverse Sine

Tags

CCSS.HSG.SRT.C.7

What mode should the calculator be in to find angle A?

• Scientific

• Gradient

• Degree

• Radian

Tags

CCSS.HSG.SRT.D.10

CCSS.HSG.SRT.D.11

Which law can be used to find another angle after finding the largest angle?

• Law of Tangents

• Pythagorean Theorem

• Law of Sines

• Law of Cosines

Tags

CCSS.8.G.A.5

What is the sum of the interior angles of a triangle?

• 90 degrees

• 180 degrees

• 270 degrees

• 360 degrees

Tags

CCSS.8.G.A.5