The circumference of a circle is found by the formula C=pi(d) where d is the diameter of the circle. Does circumference vary directly as diameter? If so what is the constant of variation

Yes, π.

Yes, the circumference of a circle does vary directly as the diameter. In other words, if you double the diameter of a circle, the circumference will also double.

To find the constant of variation between circumference and diameter, let's rearrange the formula for circumference.

C = πd

Divide both sides of the equation by d:

C/d = π

The left side of the equation, C/d, represents the ratio of circumference to diameter and it will always be equal to the constant π (approximately 3.14).

Therefore, the constant of variation between circumference and diameter is π (pi).