Question

The center of a circle with a radius of three units is (1,1). Which of these points is on the circle?
A. (4,4)
B. (-2,1)
C. (-4,1)
D. (3,0)

Answer 1

Plot all the points on an xy plane or use the distance formula. Whichever point is a distance of 3 units from 1,1 is the correction solution.

Answer 2

so A????

Answer 3

wait a sec. Let me do it

Answer 4

That's not 3 distance units. Did you use the distance formula?

Answer 5

It's B

Answer 6

well...plotting all the point and visualize everything will give you a feeling for the solution but the real way to do it is with the distance formula...which i cant recall...but A is a trap!

Answer 7

Actually hat, the quickest way is to plot the points on an xy plane. That's why I know the answer is B

Answer 8

yes i would go with B as well...just a huntch

Answer 9

Distance Formula takes longer, thats why I suggested plotting on xy plane first.

Answer 10

distance formula takes longer but if u dont have designing tools around you distance formula can be a lot faster

Answer 11

Also check visually points that line up with the centre, like (*,1), or (1,*). The distance formula reduces to the difference. B is such a case.
However, we don't always get lucky this way.

Answer 12

I don't consider graph paper a "designing tool"

Answer 13

By default, if you're taking a math class, you should have graph paper handy