ACT Math 2.4 Coordinate Geometry
ACT Math: Coordinate Geometry Drill 2, Problem 4. What is the equation for the circle in the video?
|ACT Math||Coordinate Geometry|
|ACT Mathematics||Coordinate Geometry|
|Algebra||Coordinates and Graphs|
|Coordinate Geometry||Graphs of points, lines, polynomials, and circles|
The relations between equations and graphs
|Foreign Language||Arabic Subtitled|
|Product Type||ACT Math|
(x -- h)2 + (y -- k)2 = r2 where (h, k)
is the center of the circle and r is the radius.
We just have to figure out the h, k and r. One thing in our court that should make it
easier is that the circle's middle is the origin, or point 0, 0.
We can just plug those in for starters, which gives us the equation:
Quantity x minus 0 squared plus quantity y minus 0 squared equals r squared.
Get rid of the 0's and we have x squared plus y squared equals.....
Well, we know r already because the problem gives us 4 and negative 4 here and here...
so this distance is the radius
The circle's equation has to equal r squared... which is 16.
So the answer is D.