Question

What is the diameter of the following?

(x - 9)2 + (– 4)2 = 36
(by the way the 2’s are actually squared but it won’t let me put that on this app:( )

Answer 1

12

Explanation:

The equation of a circle in standard form is

(x - h)² + (y - k)² = r²

where (h, k) are the coordinates of the centre and r is the radius

(x - 9)² + (y - 4)² = 36 ← is in standard form

with r² = 36 ⇒ r =
`√(36)` = 6

diameter = 2 × r = 2 × 6 = 12