Let the following predicates be given in the domain of all triangles. R(x)="xisarighttriangle."B(x)="xhasanobtuseangle." Consider the following statements: S1=(x)(R(x)B(x)) S2=(x)(R(x)B(x)) a. Write a proof sequence to show that S1S2. Show the rule used in each step. b. Write S1 in ordinary English. c. Write S2 in ordinary English