Pre-Calculus - Using the difference of two angles to evaluate the an angle for cosine, cos195

The video tutorial covers the evaluation of trigonometric functions using coordinate points and angles on the unit circle. It explains the subtraction of angles and the calculation of cosine and sine values for specific angles. The instructor emphasizes the importance of paying attention to avoid common mistakes, such as mixing up angles. The tutorial concludes with a demonstration of final calculations and factoring techniques.

What is the formula for the cosine of the difference of two angles?

• cos(U - V) = cos(U) * cos(V) - sin(U) * sin(V)

• cos(U - V) = cos(U) * cos(V) + sin(U) * sin(V)

• cos(U - V) = sin(U) * cos(V) - cos(U) * sin(V)

• cos(U - V) = sin(U) * sin(V) + cos(U) * cos(V)

What are the coordinates of 30 degrees on the unit circle?

• (1/2, sqrt(3)/2)

• (sqrt(3)/2, 1/2)

• (sqrt(2)/2, sqrt(2)/2)

• (-sqrt(2)/2, -sqrt(2)/2)

How do you determine the coordinates of 225 degrees on the unit circle?

• By using the coordinates of 90 degrees directly

• By using the coordinates of 60 degrees directly

• By reflecting the coordinates of 30 degrees in the fourth quadrant

• By reflecting the coordinates of 45 degrees in the third quadrant

What is the cosine of 225 degrees?

• 1/2

• -sqrt(2)/2

• -1/2

• sqrt(2)/2

What is the result of multiplying the cosine of 225 degrees and the cosine of 30 degrees?

• -sqrt(2)/4

• sqrt(6)/4

• sqrt(2)/4

• -sqrt(6)/4