Question

1. Drag and drop an answer to each box to correctly complete the derivation of a formula for the area of a sector of a circle.

Answer 1

Answer:-

Central angle , Ф/2π , A = Ф/2 r²

The ratio is 1/3 , V = 1/3 Bh

The equation of the circle in standard form is (x - 4)² + (k - 1)² = 25

Step-by-step explanation:

* Lets revise the rules of the area of the sector of a circle

- The area of the sector which has a central angle Ф° is

  (Ф°/360°) × πr², where 360° is the measure of the circle and r is

  the radius of the circle

- The area of the sector which has a central angle Ф radians is

  (1/2) r²Ф

* Lets complete the missing in the 1st picture

- The ratio of the sector's area A to the circle's area is equal to the

  ratio of the central angle to the measure of a full rotation of the circle

- A full rotation of a circle is 2π. This proportion can written as

 A/πr² = Ф/2π

- Multiply both sides by πr² to get A = Ф/2 r² where Ф is the measure

 of the central angle and r is the radius of the circle

* Lets revise the rules of the volume of the prism and the volume

 of the pyramid, where they have the same base and height

- The volume of the prism = area of the base × its height

- The volume of the pyramid = 1/3 × area of the base × its height

- From them the ratio of the volume of the pyramid to the volume

 of the prism is 1/3

- The formula of the volume of the prism is V = Bh, where B is the

  area of the base and h is the height, the formula of the volume

  of the pyramid is V = 1/3 Bh

* Lets revise the standard form of the equation of a circle with

 center (h , k) and radius r

- The equation is: (x - h)² + (y - k)² = r²

∴ x² - 2hx + h² + y² - 2ky + k² - r² = 0

∵ x² - 8x + y² - 2y - 8 = 0

- Lets equate the two equation

∴ x² - 2hx + h² + y² - 2ky + k² - r² = x² - 8x + y² - 2y - 8 = 0

∵ -2h = -8 ⇒ ÷ -2

∴ h = 4

∵ -2k = -2 ⇒ ÷ -2

∴ k = 1

∵ h² + k² - r² = -8

∴ (4)² + (1)² - r² = -8

∴ 16 + 1 - r² = -8

∴ 17 - r² = -8 ⇒ subtract 17 from both sides

∴ -r² = -15 × -1

∴ r² = 25

* Substitute the values of h , k , r in the equation of the standard

 form of the circle

∴ (x - 4)² + (k - 1)² = 25

* The equation of the circle in standard form is (x - 4)² + (k - 1)² = 25