If the divorce did not take place according to the Sharia, then in order for it to be valid it must be undertaken in the way prescribed by the Sharia, including pronouncing the formula of divorce. A written document is not sufficient.
Religious adulthood is recognized for the male by any of the following three signs, whichever happen first:
1. The presence of hard hair on his face or in the pubic area.
2. The release of semen, whether it was during a wet dream or when awake.
3. The completion of fifteen lunar years.
The female reaches adulthood when she completes the age of nine lunar years.