The radius of a circle is found by doing this :
circumference ÷ 6.28 = radius
The circumference here is 17.27 feet :
circumference ÷ 6.28 = radius
so
17.27 ÷ 6.28 = 2.75
The radius of the circle is 2.75 feet.
2/3 of 300 is 200.
200 +40 = 240.
the total amount of seats minus the amount filled
300 - 240 = 60
That means that there are 60 seats remaining.
<u>Answer-</u>
<em>The correct answer is</em>
<em>∠BDC and ∠AED are right angles</em>
<u>Solution-</u>
In the ΔCEA and ΔCDB,

As this common to both of the triangle.
If ∠BDC and ∠AED are right angles, then 
Now as
∠BCD = ∠ACE and ∠BDC = ∠AED,
∠DBC and ∠EAC will be same. (as sum of 3 angles in a triangle is 180°)
Then, ΔCEA ≈ ΔCDB
Therefore, additional information can be used to prove ΔCEA ≈ ΔCDB is ∠BDC and ∠AED are right angles.
Answer: Angle 4
Step-by-step explanation:
The angle of depression is formed by the line of sight and the horizontal line tangent to the top of the observer.