Learning to apply the law of cosines when given one obtuse angle

The video tutorial explains how to use the Law of Cosines to solve for a side of a triangle when an angle is known. It demonstrates the step-by-step process of plugging values into the formula and calculating the result. The tutorial then transitions to using the Law of Sines to find an unknown angle, emphasizing the importance of not rounding intermediate values. Finally, it calculates the remaining angles of the triangle, ensuring a comprehensive understanding of solving triangles using trigonometric laws.

When is the law of cosines particularly useful?

• When no sides are known

• When all three sides of a triangle are known

• When only angles are known

• When two sides and an angle are known

What is the formula for the law of cosines?

• a^2 = b^2 + c^2 + 2bc * cos(A)

• c^2 = a^2 + b^2 - 2ab * cos(C)

• b^2 = a^2 + c^2 - 2ac * cos(B)

• a^2 = b^2 + c^2 - 2bc * cos(A)

Why is it important not to round intermediate results in calculations?

• It ensures the final result is more accurate

• It makes the calculations easier

• It saves time

• It is not important

What is the next step after finding b using the law of cosines?

• Find the hypotenuse

• Calculate the perimeter of the triangle

• Find the area of the triangle

• Use the law of sines to find unknown angles

How do you find angle A using the law of sines?

• a / sin(A) = b / cos(B)

• a / sin(A) = c / sin(C)

• a / sin(A) = b / sin(B)

• b / sin(B) = c / sin(C)

What is the significance of the sum of angles in a triangle?

• It is always 360 degrees

• It is used to find the hypotenuse

• It is always 180 degrees

• It helps in finding the area

What is the final step to find angle C?

• Subtract angles A and B from 180 degrees

• Add angles A and B

• Divide angles A and B

• Multiply angles A and B