If r={(x, y)|x^2+y^2=a^2} is a relation then its inverse r'={(x, y)|y^2+x^2=a^2} would be same as r, why is that, can someone please explain it with detail.

Astandard deck of cards contains 52 cards. one card is selected from the deck. (a) compute the probability of randomly selecting a diamond or heart. (type an integer or a decimal rounded to three decimal places as needed.) (b) compute the probability of randomly selecting a diamond or heart or club. (type an integer or a decimal rounded to three decimal places as needed.) (c) compute the probability of randomly selecting queen or club. (type an integer or a decimal rounded to three decimal places as needed.)