Which expression is equivalent to the following complex fraction? 1/x-1/y / 1/x+1/y a. y+x/y-x b. (y-x)(y+x)/ x^2 y^2 c. x^2 y^2/ (y+x) (y+x) d. y-x/y+x

(D)

Explanation:

Just a note on writing down these expressions: I recommend using parentheses whenever you can to avoid misinterpretation. An expression 1/x-1/y / 1/x+1/y could be interpreted by someone as 1/x-(1/y / 1/x)+1/y, which is a different thing.

ca = ec

cpctc makes it so that corresponding parts of the triangle you proved to be equal are equal, the other options aren't part of the part of the triangles you proved to be equal.