Answer:
a) 42.056 cm b) 1,388.435 cm^2
Explanation:
a)
Circumference (c) = Diameter (d) x pi
In this case, d = c - 90.
You can plug in (d pi) for the c: d = d pi - 90
Subtract the d and 90 from both sides: 90 = d pi - d
Factor out the d: 90 = (pi - 1) d
(Pi - 1) is approximately 2.14: 90 = 2.14 d
Divide both sides by 2.14: 90/2.14 = d
d (approximately) = 42.056 cm
b)
Area of a circle (A) = Radius squared (r^2) x pi
Radius is half the diameter. The diameter is 42.056, therefore the radius is 21.028.
A = pi (21.028 cm) ^2
A = 3.14 (442.176 cm^2)
A (approximately) = 1,388.435 cm^2