A triangular display of identical coins is made in such a way that the first row has 1 coin, the second row has 2 coins, the third row has 3 coins and so on. If the total number of coins used is 210, determine the number of rows in the display.
(i) Form an equation involving the total number of coins and the number of rows.
(ii) Solve the equation to find the required number of rows.