The center of circle [tex]\( Q \)[/tex] has coordinates [tex]\((3, -2)\)[/tex]. If circle [tex]\( Q \)[/tex] passes through [tex]\( R(7, 1) \)[/tex], what is the length of its diameter?

A. 50
B. 25
C. 10
D. 5



Answer :

To find the length of the diameter of the circle [tex]\( Q \)[/tex] centered at [tex]\( (3,-2) \)[/tex] and passing through the point [tex]\( R(7,1) \)[/tex], we follow these steps:

1. Identify the center and a point on the circle:
- Center of the circle [tex]\( Q \)[/tex]: [tex]\( (3, -2) \)[/tex]
- Point [tex]\( R \)[/tex] on the circle: [tex]\( (7, 1) \)[/tex]

2. Calculate the radius of the circle:
- To find the radius, we use the distance formula to calculate the distance between the center of the circle and point [tex]\( R \)[/tex]. The distance formula is:
[tex]\[ d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2} \][/tex]
- Plug in the coordinates of the center [tex]\( (3, -2) \)[/tex] and point [tex]\( R(7, 1) \)[/tex]:
[tex]\[ d = \sqrt{(7 - 3)^2 + (1 + 2)^2} \][/tex]
[tex]\[ d = \sqrt{(4)^2 + (3)^2} \][/tex]
[tex]\[ d = \sqrt{16 + 9} \][/tex]
[tex]\[ d = \sqrt{25} \][/tex]
[tex]\[ d = 5 \][/tex]
- The radius of the circle is [tex]\( 5 \)[/tex] units.

3. Calculate the diameter of the circle:
- The diameter [tex]\( D \)[/tex] of a circle is twice the radius. So:
[tex]\[ D = 2 \times \text{radius} \][/tex]
[tex]\[ D = 2 \times 5 \][/tex]
[tex]\[ D = 10 \][/tex]

4. Choose the correct answer:
- From the given options, the length of the diameter is [tex]\( \boxed{10} \)[/tex].