Study Guide Unit 4B Geometry (Circles and Surface Area) SY24-25

Front

What is the formula for the circumference of a circle?

Back

C = πd or C = 2πr, where C is the circumference, d is the diameter, and r is the radius.

Front

How do you find the diameter of a circle if you know the circumference?

Back

Diameter can be found using the formula d = C/π.

Front

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

Back

The diameter is twice the length of the radius: d = 2r.

Front

What is the formula for the area of a circle?

Back

A = πr², where A is the area and r is the radius.

Front

How do you find the radius of a circle if you know the area?

Back

Radius can be found using the formula r = √(A/π).

Front

What is the area of a square with a side length of 8 m?

Back

Area = side² = 8 m × 8 m = 64 m².

Front

If the area of a circle is 50.24 in², what is the radius?

Back

Radius can be found using r = √(A/π) = √(50.24/π) ≈ 4 in.

Front

What is the difference in area between two circles with radii 5 in and 3 in?

Back

Area of larger circle = π(5)² = 25π; Area of smaller circle = π(3)² = 9π; Difference = 25π - 9π = 16π in².

Front

What is the sum of the areas of two circles with radii 4 in and 6 in?

Back

Area of first circle = π(4)² = 16π; Area of second circle = π(6)² = 36π; Sum = 16π + 36π = 52π in².

Front

What is the approximate value of π?

Back

π is approximately 3.14.