(1) the diameter is 20 inches whats the radius? And whats the circumference?
Radius is half the diameter, Answer: 10 inches
Circumference is pi times the radius, Answer: 10π inches
I won't bother with the approximation, though this one is easy, 31.4159 inches. I'll leave the rest of the calculator work to you if necessary.
(2) the diameter 11 inches whats the radius? And whats the circumference?
Radius half, Answer: 5.5 inches. Circ: 5.5π inches
(3) the diameter 3.5 inches whats the radius? And whats the circumference?
Radius, 1.75 inches. Circ: 1.75π inches
The square root of a whole number will be rational if the whole number is a perfect square (i.e 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144 etc) and irrational otherwise.
Rational number is a number that can be described as m/n
so a fraction can be a rational number, 0.8=4/5
Irrational numbers can't be written as a fraction
The part about the number having to be a perfect square is still correct, if it's not a prefect square than it will just keep going(a decimal that never ends)
for example the square root of 0.64 is 0.8
and the square root of 10 is 3.162277...
as you can see the 0.64 one ends and is rational, whereas the 10 one just keeps going and is irrational.
Imagine A'V' is part of the dilated figure, and AV is part of the original figure.
A'V' = 3.2
AV = 3.2 + 4.8 = 8
A'V'/AV = 3.2/8 = 2/5
Answer: First choice, 2/5.
