Question

Which is an equation of a circle with center (2, -1) that passes through the point (3, 4)?

Answer 1

Let A be (2,-1) & B be (3,4). The radius of the circle is AB. Let's calculate it

AB =√{(3-2)²+(4+1)²]  = √26

Now the standard form of the equation of a circle:

(x-h)²+(y-k)² = R²

(x-2)²+(y-1)² = 26