Hello!
You can use the Pythagorean Theorem
[tex] a^{2} + b^{2} = c^{2} [/tex]
C is the hypotenuse which is the line across the diameter
a and b are the other sides
You have to find the bottom side of the triangle
9 - 6 = 3
Put in the values you know
[tex] 9^{2} + 3^{2} = c^{2} [/tex]
Square the numbers
[tex]81 + 9 = c^{2} [/tex]
Add
[tex]90 = c^{2} [/tex]
take the square root of both sides
[tex] \sqrt{90} = c[/tex]
The answer is [tex]C) \sqrt{90} [/tex]
Hope this helps!
