What is the length of the diagonal of the square shown below? 7
45°
7
190
7
A. 49
B. 14
C. 71
D. 7
E. 7
F. 7.

The answer is Letter F

This answer is Letter F

i assume you mean  3x^2 + 16y = 0

so y =  -3/16 x^2

The vertex is at the origin (0,0)  answer

x^2 = -16/3 y

compare with standard form x^2 = 4ay:-

the focus y coordinate of the  a =  -16/3  / 4

= -16/12 =  -4/3   so the focus is (0, -4/3) answer

and the directrix is y = 4/3  answer