On my homework it says "find the missing dimension of the circle," so if the circumference is 43.5 inches, the diameter is __? My teachers didn't explain this very well and I'm pretty confused.

The formula for circumference is 2πr, where r = radius.

If you know the circumference is 43.5, then:

43.5 = 2πr

solve, first divide both sides by 2

21.75 = πr

next, divide both sides by π (or the approximation 3.14)

r ≈ 6.93

diameter is twice the radius (d = 2r)

d = 2r

d = 2 x 6.93

d ≈ 13.86

The diameter is about 13.6 inches