Question

Write the standard equation of the circle with center (-3,5) && diameter of 10.

A. (X+3) + (Y-5)^2 = 25
B. (X+3) + (Y-5)^2 = 100
C. (X-5) + (Y+3)^2 = 5
D. (X-3) + (Y+5)^2 = 85

Answer 1

(x+3)^2+(y-5)^2=25

Answer 2

how did you get that ? @Federica

Answer 3

@jim_thompson5910

Answer 4

@apoorvk

Answer 5

Hmm..
for a circle with center at (a,b) and radius 'r' the equation is:
\[(x-a)^2 + (y-b)^2 = r^2\]

Now you have the coordinates of the center, as well as the diameter, from which you can find the radius.

Helps?

Answer 6

Yes, you´re right apoorvk.

Answer 7

ok well i plugged in the solution for A but -3 + 3 = 0 && 5+ -5 = 0

Answer 8

@apoorvk . i think its B

Answer 9

you don't even need to plug in, just substitute values for 'a', 'b' and 'r' in the equation formula.

Answer 10

umm, slight bit of a mistake @Senior012 , the *diameter* is 10, but you need to substitute the *radius* in there.

Answer 11

sorry i was looking at a different question.. C ?

Answer 12

wait D ?

Answer 13

well, radius = 10/2 = 5

so, r^2 = 5^2 = 25

put this in place of r^2

Answer 14

Lol, stay calm, you're getting confused! Cool man :)

Answer 15

ok so my guess is A && C ? right or wrong ? nothing else makes sense

Answer 16

C makes no sense, since r=5, but r^2 = 25. (Have a look at the formula again.)
so that leaves us with A!

Answer 17

helps eh?

Answer 18

But why the term of x is not squared?

Answer 19

Hmm.. good point, I didn't even notice it.. Is that a typo @Senior012 ?