1. **State the problem:** We need to find the diameter of a circle given its radius. 2. **Formula:** The diameter $d$ of a circle is twice the radius $r$. This is expressed as: $$d = 2r$$ 3. **Apply the formula:** Given $r = 7$ cm, substitute into the formula: $$d = 2 \times 7$$ 4. **Calculate:** $$d = 14$$ 5. **Answer:** The diameter of the circle is 14 cm.