While I was searching for the longer form of an adjective рад, I found the following sentence:
рад, рада, радо, рады are short form adjectives, and also the only commonly used short form adjective in Modern Russian that does not have a long form.
This suggests that there existed a longer form of рад as well. Assuming this author is correct, is радый the corresponding long form or is there another?
Also, is the use of рад preferred to радостный, when used as a predicate?