Question

The black figure is an ellipse, and the black line segment is is major axis. What is the length of the blue line segment?

Answer 1

Answer:

D

Step-by-step explanation:

The formula we need to solve this is:

$d_1+d_2=2a$

Where

$d_1$  is the distance from one focus to the vertex

$d_2$  is the second distance from another focus to same vertex

Note: Here, vertex point is the point on top. The common point from which the RED and BLUE line meets the 2 foci

$a$  is half the length of the major axis (which is 9 here since total major axis is given as 18)

Now we can plug into the equation and solve:

$d_1+d_2=2a\\8.5+d_2=2(9)\\8.5+d_2=18\\d_2=18-8.5\\d_2=9.5$

D is the correct answer.