Answer:
F = 110°
I'm not sure, but since no one answered, here it goes...
Step-by-step explanation:
∵ FD = FE (Given in Diagram)
∴ ΔDFE is isosceles , ∴m∠E = m∠D
1 ) 3x + 14 = 5x
14 = 5x - 3x
14 = 2x
14 / 2 = x
7 = x
m∠E = 3*7 + 14 = 35°
m∠D = 5*7 = 35°
m∠F = 180 - (35+35)
m∠F = 110°
Answer:
Option B. 
Step-by-step explanation:
step 1
Find the central angle of the shaded sector
Remember that the diameter divide the circle into two equal parts ( 180 degrees each part)
so
Let
x -----> the measure of the central angle of the shaded sector
∠x+72°=180°
∠x=180°-72°=108°
step 2
Find the area of the circle
The area of the circle is

we have

assume

substitute


step 3
Find the area of the shaded sector
Remember that the area of the complete circle subtends a central angle of 360 degrees
so
by proportion find the area of a sector by a central angle of 108 degrees

6.4n^2 is correct. math papa helps