Find the exact value by using a half-angle identity.cos 
A. 
B. 
C. 
D. 
Answer: C
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Find the standard-form equation of the ellipse centered at the origin and satisfying the given conditions.An ellipse with a vertex at (0, 7) and a focus at (0, -3).
A. 
+ 
= 1
B. 
+ 
= 1
C. 
+ 
= 1
D. 
+ 
= 1
Provide an appropriate response.Let U represent the set of prisoners in United States prisons. Let A represent the set of prisoners in California state prisons. Describe A'.
A. The set of prisoners in all the prisons in the world. B. The set of prisoners in California state prisons who aren't United States citizens. C. The set of United States prisoners that are not in California state prisons. D. The set of prisoners in California state prisons.
Which of the following physical situations would best be modeled by the graph?
A. The length y of a shadow cast by a tree between sunrise and noon, where t is the angle of elevation of the sun.
B. The monthly average ocean temperature y in degrees Fahrenheit during month t, where t = 1 corresponds to January.
C. The length y of a shadow cast by a horizontal flagpole on a vertical wall between sunrise and noon, where t is the angle shown.
D. The number of hours y of sunlight during month t, where t = 1 corresponds to January.
Multiply and simplify. Assume that all variables represent positive real numbers.
? 
A. 4xy8
B. 4xy4
C. 4y4
D. 2xy4