Circle Flashcards
What is the formula for the circumference of a circle?
The circumference of a circle is given by the formula C = 2πr, where r is the radius.
True or False: The diameter of a circle is twice the radius.
True.
Fill in the blank: The area of a circle is calculated using the formula A = π__^2.
r
What is the area of a circle with a radius of 5 units?
The area is 25π square units.
Multiple choice: Which of the following is the correct formula for the area of a circle? A) A = 2πr B) A = πr^2 C) A = πd D) A = 2r
B) A = πr^2
What is the relationship between the radius, diameter, and circumference of a circle?
The diameter is twice the radius, and the circumference is π times the diameter.
True or False: The circumference of a circle can be calculated using the diameter.
True.
Fill in the blank: The area between two concentric circles is known as the area of the ___.
annulus
What is the formula for the area of an annulus?
The area of an annulus is A = π(R^2 - r^2), where R is the outer radius and r is the inner radius.
Multiple choice: If the radius of a larger circle is 10 and the radius of a smaller circle is 4, what is the area of the annulus? A) 36π B) 20π C) 60π D) 80π
A) 36π
What does the symbol π represent?
π represents the mathematical constant approximately equal to 3.14159.
True or False: The area of a circle increases with the square of the radius.
True.
Fill in the blank: The circumference can also be calculated using the formula C = π__.
d
What is the circumference of a circle with a diameter of 8 units?
The circumference is 8π units.
Multiple choice: Which of the following correctly describes the radius? A) The distance from the center to the edge B) The distance across the circle C) Half the diameter D) Both A and C
D) Both A and C
If the radius of a circle is doubled, what happens to the area?
The area becomes four times larger.
True or False: The area of a circle is directly proportional to the square of its radius.
True.
Fill in the blank: The circumference of a circle is directly proportional to its ___.
diameter
What is the area of a circle with a radius of 3 units?
The area is 9π square units.
Multiple choice: What is the unit of measurement for area in the context of circles? A) Units B) Units^2 C) Units^3 D) None of the above
B) Units^2
True or False: The area of a circle can be negative.
False.
What is the circumference of a circle with a radius of 1 unit?
The circumference is 2π units.
Fill in the blank: To find the area of a circle, you multiply π by the square of the ___.
radius
Multiple choice: What happens to the circumference if the radius is halved? A) It remains the same B) It doubles C) It is halved D) It quadruples
C) It is halved
True or False: The area between two concentric circles can be calculated using the radii of both circles.
True.
