Understanding the Law of Cosines

The video tutorial explains how to find the length of angle A in a triangle using the law of cosines. It begins by labeling the triangle's angles and sides, then applies the law of cosines to set up an equation. The tutorial walks through simplifying the equation and solving for cosine A, followed by using a calculator to find the angle in degrees. The process is detailed step-by-step, ensuring clarity in understanding the application of the law of cosines.

What is the length of side a in the triangle?

• 12 units

• 17 units

• 23 units

• 15 units

Which side is opposite to angle B?

• Side b

• Side a

• None of the above

• Side c

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

What is the value of 12 squared plus 23 squared?

• 529

• 673

• 289

• 144

What is the next step after simplifying the equation to 289 = 673 - 552 cos A?

• Subtract 673 from both sides

• Divide both sides by 552

• Add 673 to both sides

• Multiply both sides by 552

What is the result of dividing -384 by -552?

• 0.696

• 0.694

• 0.6957

• 0.695

What function is used to find angle A from cosine A?

• Sine

• Inverse Cosine

• Inverse Sine

• Tangent

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

• Gradient

• Degree

• Radian

• None

What is the approximate value of angle A in degrees?

• 45.00

• 46.00

• 45.92

• 44.92

What is the purpose of using the inverse cosine function in this context?

• To find the measure of angle A

• To find the measure of angle B

• To find the length of side a

• To find the length of side b