The answer is A. A, D the reason being, is because polygons have sides C, and B have no sides so we can eliminate those immediately.
7:4 is the constant and is your answer
False if you take xyou can get answer
We know in these kind of triangles that have a 90 degrees angle, we can do:

so the first question:

and then:

so , when you want to rationalize , usually you must multiply the irrational factor as 1:

so , now multiply:

in the next question,we know negative numbers in radical don't have any solution so 2 is correct,
T=2 the solution set is t=2