Circles Flashcards

1
Q

What is the formula for the circumference of a circle?

A

C=πD
or
C=2πr

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2
Q

What is the formula for the area of a circle?

A

A=πr2

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3
Q

What is the value of π to 2 decimal places?

A

3.14

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4
Q

How do you find the arc length?

A
  • Find the circumference of the full circle
  • Find the fraction of the circumference by using ‘angle/360’
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5
Q

How do you find the perimeter of a part circle?

A
  • Find the circumference of the full circle
  • Find the fraction of the circumference by using ‘angle/360’
  • Add the arc length and the two radii together
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6
Q

How do you find the area of a part circle?

A

Find the area of the full circle

Find the fraction of the area by using
‘angle/360’

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7
Q

How do you find the diameter from a given circumference?

A

Substitute into the formula
C=πD

and solve
(Divide by π)

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8
Q

How do you find the radius from a given area?

A

Substitute into the formula
A=πr2

and solve
(Divide by π and then √ )

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9
Q

What are the steps to find the area of the shaded segment?

A

Calculate:
Area of full circle
Area of sector (quarter circle)
Area of triangle (1/2 base x Height)
Subtract the Triangle from the Sector

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