1. **State the problem:** Fully factorise the expression $$36c^2 - d^2$$. 2. **Recognize the formula:** This is a difference of squares, which follows the rule $$a^2 - b^2 = (a - b)(a + b)$$. 3. **Identify squares:** Here, $$36c^2 = (6c)^2$$ and $$d^2 = (d)^2$$. 4. **Apply the difference of squares formula:** $$36c^2 - d^2 = (6c - d)(6c + d)$$. 5. **Check for further factorisation:** Neither $$6c - d$$ nor $$6c + d$$ can be factored further. **Final answer:** $$36c^2 - d^2 = (6c - d)(6c + d)$$.