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8-81.

Use your findings from problem 8-79 to answer the questions below. Recall that the diameter of a circle is a segment with endpoints on the circle that passes through the center. The length of the segment is also called the diameter. Homework Help ✎

  1. What is the area of a circle with radius units?

    For a circle, area .

    area units

  2. What is the circumference of a circle with diameter units?

    For a circle, circumference .

  3. If the area of a circle is square units, what is its diameter?

    Use the formula for area of circle and solve for the radius.

    units
    What is the diameter?

  4. If the circumference of a circle is units, what is its area?

    Use the circumference formula and solve for the diameter.

    What is the radius? Use the radius to calculate the area.