The area of D is given by:

The average value of f over D is given by:
Answer:
-(4/7)
or
if you are above 11th standard
4/7i
Answer:
See Explanation
Step-by-step explanation:
According to the Question,
Steps of construction:
- Step I - Draw a line segment AB = 7 cm with the help ruler.
- Step II - with vertex A, by using compass take more than half of AB and draw arcs, one on each side of AB.
- Step III - with vertex B, by using a compass with the same length, cut the previous arcs at X and Y respectively.
- Step IV - with help of the ruler join the points X and Y Thus XY is the perpendicular bisector of line AB.
(For Diagram please find in attachment)
By definition of the trig functions,


We have
, so
, and
, so
.
Just to check: we should have

by the Pythagorean theorem. Indeed,
