The diameter of a circle (or in this case a bicycle wheel) is how long it is from one side of the circle striaght across to the other side. The radius is half the diameter. So if the diameter is 34, then the radius would be 17.
The common way of transforming the general form to the standard form is by using the completing the square method. But there is also a neat shortcut to knowing the h, k and r values right away.
The general formula is:
x²+y²+Dx+Ey+F = 0
x² + y² + (-2h)x + (-2k)y + (h²+k²-r²) = 0
Solving for h:
-2h = 42
h = -21
Solving for k:
-2k = 38
k = -19
Solving for r:
-47 = (-21)² + (-19)² - r²
r = √849
Standard form of given circle is:
(x+21)² + (y+19)² = 849
Answers:
1) B
2) B
3) B
4) D
Answer:
Sorry about the incorrect answer
