Answer:
Part 1: r = √(A/π)
Part 2: 4.15 cm
Explanation:
Part 1
The area of a circle is given by;
Area = π r²
A = πr²
dividing both sides by π
r² = A/π
Find the square root on both sides of the equation
r = √(A/π)
Part 2
where π = 22/7 and
r is the radius os the circle
Area = 54 cm²
πr² = 54
22/7 × r² = 54
Multiplying both sides of the equation by 7/22
7/22 × 22/7 ×r² = 54 ×7/22
r² = 189/11
= 17.181818..
r = √17.181818
= 4.145
Answer to the nearest hundredth = 4.15 cm