Answer:
Part 4) 
Part 10) The angle of elevation is 
Part 11) The angle of depression is 
Part 12)
or 
Part 13)
or 
Step-by-step explanation:
Part 4) we have that

The angle theta lies in Quadrant II
so
The sine of angle theta is positive
Remember that

substitute the given value




Part 10)
Let
----> angle of elevation
we know that
----> opposite side angle theta divided by adjacent side angle theta

Part 11)
Let
----> angle of depression
we know that
----> opposite side angle theta divided by hypotenuse


Part 12) What is the exact value of arcsin(0.5)?
Remember that

therefore
-----> has two solutions
----> I Quadrant
or
----> II Quadrant
Part 13) What is the exact value of 
The sine is negative
so
The angle lies in Quadrant III or Quadrant IV
Remember that

therefore
----> has two solutions
----> IV Quadrant
or
----> III Quadrant
<em>A ratio camparing two quantities with different kinds of units is a ratio that tells the rate of change of one variable with a change in other variable.</em>
Answer:
254.3 mm^2
Step-by-step explanation:
Area of a circle: A = π*r^2
π (pi) = 3.14
r (radius) = 9 mm
Substitute 3.14 for pi and 9 for radius:
A = π*r^2
A = 3.14*9^2
A = 3.14*81
A = 254.34 mm^2
Round to the nearest tenth:
254.34 ==> 254.3
Therefore, our final answer is 254.3 mm^2
Hope this helps!
-1.5 should be your answer.
if wrong I apologize.