Answer:
C
Step-by-step explanation:
The formula for the area of a trapezoid is: 
(height)(sum of parallel lines)
Thus, the formula in this question would be: (4)(4+8) which is option C
Answer:
E
Step-by-step explanation:
The problem says that triangle BDC lies in the plane k, which means that whatever angle is formed by another point beyond this plane with any of the three segments that form BDC (BD, DC, and BC) is the same as the angle formed by the line connecting the point and the plane.
Here, we're given that AD⊥DC, which means AD forms a 90° angle with DC. Then, since DC is already on the plane, we already know for sure that AD is definitely perpendicular to plane k.
Thus, the answer is E (none of these).
Answer:
3.92
To find the mean absolute deviation of the data, start by finding the mean of the data set.
Find the sum of the data values, and divide the sum by the number of data values.
Find the absolute value of the difference between each data value and the mean: |data value – mean|.
Find the sum of the absolute values of the differences.
Divide the sum of the absolute values of the differences by the number of data values.
