Alicia's Reflection #31

Alrighty so we took our exam on flatland which was easy for the most part. I am going to review some material on circles because I kind of forgot this chapter.

This is the standard form of a circle: (x-h)^2+(y-k)^2=r^2
The center of a circle is: (h,k)
The radiusis represented by: r

*Find the center and radius of the circle.

1.) (x-3)^2+(y+7)^2=19
center: (3,-7)
radius: squareroot of 19

*Find the intersection of the circle.

1.) x^2+4^2-25 and y=2x-2

a) y=2x-2
b) x^2=(2x-2)^2=25
c) x^2+4x^2-8x+4=25

5x^2-8x+4=25
5x^2-8x-21=0
5x^2-15x+7x-21=0
5x(x-3)+7(x-3)=0
(x-3)(5x+7)
x=3 x=-7/5
y=2(x)-2
2(3)-2=4
y=2(-7/5)-2=-24/5

(3,4) (-7/5,-24/5)

*Write in Standard form.

1.) Center: (4,3)
Radius: 2

(x-4)^2+(y-3)^2=4