I need help with these 2 questions

Plz which expression is equivalent to the expression below?

Sam claims that cos x =sin y if x and y are congruent angels. is sam correct ?

The sum of the first eight terms of an arithmetic progression is 9m + 14. the fifth term of the06 progression is 2m - 6, where m is a constant.given that the first term of the progression is 26,find the value of the common difference, d and thevalue of m.