Question

3.3. (08.01 LC) Find the circumference and area of a circle with a diameter of 10 inches. Leave your answers in terms of pi. (4 points) . 4. (08.01 MC) Given a cube with a volume of 27 cm3, what is the volume of a square pyramid that can fit perfectly inside the cube? (4 points)

Answer 1

1. C = 10π, A = 25π

2. 9 cm³

Explanation:

Formula for circumference = πd

Formula for area of a circle = πr²

1. Set up the equation for circumference

10π

2. Set up the equation for area (radius = 1/2diameter) and solve

π(5²) = 25π

Formula for volume of a square pyramid = 1/3s² · h

The volume of a square pyramid is equal to 1/3 of the volume of a cube. The formula for a volume of a cube is s³ which is equal to s² · h because a cube has the same side length for all sides. Therefore, the volume of a square pyramid that perfectly fits within a given cube would equal 1/3 the volume of the cube.

1. Set up the equation and solve

27 ÷ 3 = 9

Answer 2

3. The fourth: C= 10π, A = 25π

4. The third: 9 cm³

Explanation:

3.

diameter is equal two radiuses

D = 10 = 2R ⇒ R = 5

circumference: C = 2πR = 2R•π = 10π

area: A = πR² = π•5² = 25π

4.

If square pyramid fit perfectly inside cube then its base is the same as a face of cube, and the height (H) of pyramid is equal to the edge (S) of its base.

`A_p=\frac13S^2\cdot H =\frac13S^2\cdot S=\frac13S^3=\frac13A_c=\frac13\cdot27\,cm^3=9\,cm^3`