Ratios and proportions tie into each other. A ratio in real life would be basically comparing two quantities, as a proportion would be solving for the similar ratio or the equal ratio to another.
Answer:
Step-by-step explanation:
The purple circle, not ring is pi 7 squared = 153.93804
Then subtract the smaller circles area (pi 4 squared) = 153.9... - 103.6725576 =
50.2654824
Purple ring is 50.2654824
The entire circle is 4+3+3 (10) squared times pi = 314.1592654
( 50.2654824 / 314.1592654 ) x 100 = 15.999999998 %
<h3>Problem Solution</h3>
Assuming the spool is a cylinder and the circumference we're winding around is that of a circle with the given area, we can write the relation between circumference and area as
... C = 2√(πA)
10 times the circumference is then
... 10C = 20√(π·20 cm²) = 40√(5π) cm ≈ 159 cm
<h3>Formula Derivation</h3>
The usual formulas for circumference and area are
... C = 2πr
... A = πr²
If we multiply the area formula by π and take the square root, we get
... πA = (πr)²
... √(πA) = πr
Multiplying this by 2 gives circumference.
... C = 2√(πA) = 2πr
to find the radius you divide the circumference by 2pi
area is pi times radius to the 2nd power
