Final answer:
From the provided options, the correct answer is (b) 2, 4, because pi is the circumference of a circle with diameter 1 and is also the constant of proportionality relating the diameter of a circle to its circumference.
Step-by-step explanation:
The question we are addressing is which statements about π (pi) are true. Pi is a mathematical constant that represents the ratio of a circle's circumference to its diameter. The statements provided are:
- Pi is the circumference of a circle of radius 1
- Pi is the circumference of a circle of diameter 1
- Pi is the constant of proportionality relating the diameter of a circle to its circumference
- Pi is the constant of proportionality
Statement 1 is incorrect because the circumference of a circle of radius 1 is 2π, not π. Statement 2 is correct; the circumference of a circle of diameter 1 is indeed π. Statement 3 is also correct; π is the constant of proportionality that relates the diameter of any circle to its circumference, whereby C = πd. Statement 4 is too vague without context; pi can be a constant of proportionality in the specific relationship between the diameter and circumference of a circle, but without more information, this statement is ambiguous. Hence, the correct statements are 2 and 3.
Therefore, the correct answer from the provided options is (b) 2, 4.