How to find the area of a circle using diameter
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1. What is the area of a circle with a diameter of 12.6 in.?
Use 3.14 for pi and round your final answer to the nearest hundredth.
2. Which explanation can be used to derive the formula for the circumference of a circle?
a. Find the difference between the length of the circumference and diameter. Set up an equation showing the relationship of the circumference to diameter to the difference. Rearrange the equation to solve for the circumference. Substitute the diameter with 2 times the radius.
b. First find the relationship of the circumference to its diameter by finding that the length of the diameter wraps around the length of the circumference approximately π times. Use this relationship to write an equation showing the ratio of circumference to diameter equaling π . Then rearrange the equation to solve for the circumference. Substitute the diameter for 2 times the radius.
c. Find the length of the diameter and double this length. Multiply this length by π and set equal the to the circumference. Substitute the diameter for 2 times radius.
d. Find the ratio of the diameter to the area of the circle. Use this ratio to set up an equation to show this ratio equaling π . Substitute the area with 3 times the circumference. Then rearrange the equation to equal to the circumference.
3. the attatchment below.
4. What is the area of a circle whose radius is 4 ft?
a 4π ft²
b 8π ft²
c 16π ft²
d 64π ft²
5. The circumference of a circle is 7π m.
What is the area of the circle?
a 3.5π m²
b 12.25π m²
c 14π m²
c 49π m²