58. The equation [tex](x-7)^2+(y-8)^2=10[/tex] represents a circle in the standard [tex]\((x, y)\)[/tex] coordinate plane. One endpoint of a diameter of the circle has a [tex]\(y\)[/tex]-coordinate of 11. What is the [tex]\(y\)[/tex]-coordinate of the other endpoint of that diameter?

A. 1
B. 3
C. 4
D. 5
E. 8



Answer :

To find the [tex]\( y \)[/tex]-coordinate of the other endpoint of the diameter, let's carefully analyze the given information about the circle.

Given:
- The equation of the circle is [tex]\((x-7)^2 + (y-8)^2 = 10\)[/tex].
- The center of the circle is [tex]\((7, 8)\)[/tex].
- The radius of the circle is [tex]\(\sqrt{10}\)[/tex].
- One endpoint of the diameter has [tex]\( y \)[/tex]-coordinate [tex]\(11\)[/tex].

### Step-by-Step Solution
1. Identify the center's [tex]\( y \)[/tex]-coordinate:

The center of the circle is at [tex]\((7, 8)\)[/tex]. This means the [tex]\( y \)[/tex]-coordinate of the center is [tex]\( 8 \)[/tex].

2. Determine the given [tex]\( y \)[/tex]-coordinate of one endpoint of the diameter:

One endpoint of the diameter has a [tex]\( y \)[/tex]-coordinate of [tex]\( 11 \)[/tex].

3. Calculate the vertical distance between the center and the given endpoint:

The distance (or difference) between the [tex]\( y \)[/tex]-coordinate of the center (which is [tex]\( 8 \)[/tex]) and the given endpoint (which is [tex]\( 11 \)[/tex]) can be found by:

[tex]\[ \text{Difference} = 11 - 8 = 3 \][/tex]

4. Use symmetry to find the [tex]\( y \)[/tex]-coordinate of the other endpoint:

Since the given endpoint is above the center by [tex]\( 3 \)[/tex] units, the other endpoint will be symmetrically placed below the center by the same distance. Therefore:

[tex]\[ \text{Other } y \text{-coordinate} = 8 - 3 = 5 \][/tex]

Hence, the [tex]\( y \)[/tex]-coordinate of the other endpoint of the diameter is [tex]\( \boxed{5} \)[/tex].