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2, sin( θ )=6/12=1/2 => theta=30 degrees.
=> triangle is 30-60-90 
3.
Cos(45)=sqrt(2)/2
=> x=10*sqrt(2)/2=5sqrt(2)
        
             
        
        
        
Answer:
A
Step-by-step explanation:
Given
-4x²(5 - 3x² + x - 2)
 - 3x² + x - 2)
Multiply each term in the parenthesis by - 4x²
= - 20 + 12
 + 12 - 4x³ + 8x²
 - 4x³ + 8x²