Radius of a sector of a circle?

What is the radius of a sector of a circle with a central angle of measure 90° and whose area is 4π cm2?

1) 8cm

2) 4cm

3) 12cm

4) 3/4 cm

What is the radius of a sector of a circle with a central angle of measure 45° and whose area is 9/8πcm^2

1) 8cm

2) 4/3cm

3) 9/4cm

4) 3cm

2 Answers

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  • 8 years ago
    Favorite Answer

    1:

    area of a sector=90/360xπ(r^2)

    4π=0.25π(r^2)

    cut out π

    4/0.25=r^2

    taking square root on both sides:

    r=4

    so the answer is 4cm.

    2:

    area of a sector=90/360xπ(r^2)

    9/8πcm^2=45/360π(r^2)

    following the same procedure as done above

    the answer is 3cm

  • 8 years ago

    First one => Entire area = 4π * 4 = 16π cm^2 => r = 4 cm

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