The circle centered at $(2,-1)$ and with radius $4$ intersects the circle centered at $(2,5)$ and with radius $\sqrt{10}$ at two points $A$ and $B$. Find $(AB)^2$.

The first circle has equation

(x - 2)² + (y + 1)² = 4²

and the second has equation

(x - 2)² + (y - 5)² = (√10)²

Solve for (x - 2)² :

(x - 2)² + (y + 1)² = 4²   ==>   (x - 2)² = 16 - (y + 1)²

(x - 2)² + (y - 5)² = (√10)²   ==>   (x - 2)² = 10 - (y - 5)²

Then

16 - (y + 1)² = 10 - (y - 5)²

16 - (y ² + 2y + 1) = 10 - (y ² - 10y + 25)

15 - 2y - y ² = -15 + 10y - y ²

30 - 12y = 0

12y = 30

y = 30/12 = 5/2

(this is the y coordinate of A and B)

Then solve for x :

(x - 2)² = 16 - (5/2 + 1)²

(x - 2)² = 15/4

x - 2 = ± √(15/4) = ±√15/2

x = 2 ± √15/2

(these are the x coordinates for either A or B)

The intersections are the points A = (2 - √15/2, 5/2) and B = (2 + √15/2, 5/2). We want to find the squared distance between them:

(AB)² = [(2 - √15/2) - (2 + √15/2)]² + (5/2 - 5/2)²

(AB)² = (-√15)² + 0²

(AB)² = 15

One Type of Real Number would be Integers, whole numbers which do not inclue decimals. Integers looke like this: -5, -1, 0, 1, 5. Another type of Real number are rational number which are numbers that include decimals that are never end such as 1.345678 and so on. Another type of Real numberswould be Whole numbers, any non decimal number that is equal to or greater than zero such as; 0,1,2,3,4,5 and so on. The next type of Real number is natural numbers which are numbers greater than zero without decimals such as 1,2,3,4,5 etc. Lastly we have Rational numbers which are another type of Real number, they can be written as fractions some of them when in decimal form never end such as 1/3 which in decimal for would be .33333333...

Step-by-step explanation: