Given:
A circle with diameter 9 cm.
To find:
The area of the circle.
Solution:
The area of a circle is:
...(i)
Where r is the radius.
We know that, the diameter of a circle is twice than its radius.
The diameter of the given circle is 9 cm.
Substituting 
in (i), we get
Therefore, the area of the given circle is 63.6.
Your answer is D. Hope this helps!
Answer:
Q4: First, third, fifth
Step-by-step explanation:
I'm pretty sure question 5 is the first, and fourth one.
Answer:
400 m^2.
Step-by-step explanation:
The largest area is obtained where the enclosure is a square.
I think that's the right answer because a square is a special form of a rectangle.
So the square would be 20 * 20 = 400 m^2.
Proof:
Let the sides of the rectangle be x and y m long
The area A = xy.
Also the perimeter 2x + 2y = 80
x + y = 40
y = 40 - x.
So substituting for y in A = xy:-
A = x(40 - x)
A = 40x - x^2
For maximum value of A we find the derivative and equate it to 0:
derivative A' = 40 - 2x = 0
2x = 40
x = 20.
So y = 40 - x
= 40 - 20
=20
x and y are the same value so x = y.
Therefore for maximum area the rectangle is a square.
Answer:
BC
Parallel: Two sides or lines are parallel if they are lines that are always the same distance from each other and will never intersect or touch
