Flashcard - Circumference, Area, Arc Length, & Sector Area

Front

What is the formula for the area of a circle?

Back

Area = πr², where r is the radius.

Front

How do you calculate the circumference of a circle?

Back

Circumference = 2πr or Circumference = πd, where d is the diameter.

Front

What is the formula for the area of a sector of a circle?

Back

Area of sector = (θ/360) × πr², where θ is the angle in degrees.

Front

How do you find the arc length of a sector?

Back

Arc length = (θ/360) × 2πr, where θ is the angle in degrees.

Front

What is the relationship between the diameter and radius of a circle?

Back

Diameter = 2 × Radius.

Front

If the area of a circle is known, how can you find the radius?

Back

Radius = √(Area/π).

Front

What is the area of a circle with a radius of 7 cm?

Back

Area = π(7)² = 49π ≈ 153.94 cm².

Front

What is the circumference of a circle with a diameter of 10 inches?

Back

Circumference = π × 10 ≈ 31.42 inches.

Front

How do you convert the area of a sector to a percentage of the total area of the circle?

Back

Percentage = (Area of sector / Total area of circle) × 100.

Front

What is the area of a sector with a radius of 5 m and an angle of 90 degrees?

Back

Area = (90/360) × π(5)² = (1/4) × 25π ≈ 19.63 m².