Excuse me: the circumference of a semicircle is 20.56cm. What is the area of this semicircle?

Excuse me: the circumference of a semicircle is 20.56cm. What is the area of this semicircle?

20.56 △ 3.14 + 2 = 20.56 △ 5.14 = 4cm, which is the radius
4 × 4 × 3.14 △ 2 = 8 × 3.14 = 25.12 (cm2)

It is known that the circumference of the circle is 15 meters. What is the area of the circle?

2x3.14R=15,R=2.39M
S=3.14XR^2=17.91M^2

If the bottom radius of the cone is 1cm, the area of the side expanded view is 2 π cm2, and the generatrix length of the cone is 2 π cm2______ ．

According to the formula of cone side area: S = π RL, the bottom radius of cone is 1cm, and the area of side expanded view is 2 π cm2, so 2 π = π × 1 × L, the solution is: l = 2 (CM), so the answer is: 2cm

The generatrix length of the cone is 4cm, the radius of the bottom is 4cm, and the area of the expanded side view of the cone is

S = (1 / 2) × sector radius × sector arc length = (1 / 2) × L × (2 π R) = π R L = 4 × 4 × π = 16 π

Given that the generatrix length of a cone is 6 & nbsp; cm and the radius of its bottom is 3cm, the center angle of the sector in the side expansion of the cone is calculated

The radius of the bottom of the cone is 3cm, the perimeter of the bottom of the cone is 6 π, let the center angle of the sector be n °, n π × 6180 = 6 π, and the solution is n = 180

It is known that the bottom radius of the cone is 3cm, the length of the generatrix is 9cm, and C is the midpoint of the generatrix Pb. On the side of the cone, the shortest distance from a to C is______ ．

: if the circumference of the bottom surface of a cone is 6 π, then 6 π = n π × 9180, n = 120 °, that is, the center angle of the cone side development is 120 °, APB = 60 °, ∫ PA = Pb, ∫ PAB is equilateral triangle, ∫ C is the midpoint of Pb, ∫ AC ⊥ Pb, ∫ ACP = 90 °, in the cone side development, AP = 9, PC = 4.5

As shown in the figure, the bottom radius of the cone is 3cm, the length of the generatrix is 9cm, C is the midpoint of the generatrix Pb, and on the side of the cone, what is the shortest distance from a to C?

If the circumference of the bottom surface of the cone is 6 π, then 6 π = n π × 9180, ∧ n = 120 °, that is, the center angle of the cone side expansion is 120 °, APB = 60 °, PA = Pb, ∧ PAB is equilateral triangle, ∧ C is the midpoint of Pb, ∧ AC ⊥ Pb, ∧ ACP = 90 °, in the cone side expansion, AP = 9, PC = 4.5, ∧

As shown in the figure, the bottom radius of the cone is 3cm, the length of the generatrix is 9cm, C is the midpoint of the generatrix Pb, and on the side of the cone, what is the shortest distance from a to C?

If the circumference of the bottom surface of the cone is 6 π, then 6 π = n π × 9180, ∧ n = 120 °, that is, the center angle of the cone side expansion is 120 °, APB = 60 °, PA = Pb, ∧ PAB is equilateral triangle, ∧ C is the midpoint of Pb, ∧ AC ⊥ Pb, ∧ ACP = 90 °, in the cone side expansion, AP = 9, PC = 4.5, ∧

It is known that the bottom radius of the cone is 4cm, the length of the generatrix is 12cm, and C is the midpoint of the generatrix Pb

If the circumference of the bottom surface of a cone is 8 π, then 8 π = n π × 12180, ∧ n = 120 °, that is, the center angle of the developed side view of the cone is 120 degrees. ∧ APB = 60 degrees, ∧ PA = Pb, ∧ PAB is an equilateral triangle, ∧ C is the midpoint of Pb, ∧ AC ⊥ Pb, ∧ ACP = 90 degrees

It is known that the bottom radius of the cone is 4cm, the length of the generatrix is 12cm, and C is the midpoint of the generatrix Pb

If the circumference of the bottom surface of a cone is 8 π, then 8 π = n π × 12180, ∧ n = 120 °, that is, the center angle of the developed side view of the cone is 120 degrees. ∧ APB = 60 degrees, ∧ PA = Pb, ∧ PAB is an equilateral triangle, ∧ C is the midpoint of Pb, ∧ AC ⊥ Pb, ∧ ACP = 90 degrees