What is the radius of the circle whose equation is x2 + y2 = 8?

Question

anonymous · Answer

$$2\sqrt{2}$$
4
64

phi · Answer

do you know the equation for a circle ?  (look in your notes)
what is it ?

igreen · Answer

Easiest way is to graph.. https://www.desmos.com/calculator Then see where the farthest point the circle goes to the left/right.

anonymous · Answer

$$x ^{2}+y^{2}=8$$

phi · Answer

phi · Answer

you should match up your equation with
$$ x^2 +y^2 = r^2 $$
and see that
$$ r^2 = 8 $$
to find r, take the square root 
$$ r = \sqrt{8} $$

phi · Answer

you can "simplify" the square root of 8
by writing 8 as 2*2*2
$$ \sqrt{2 \cdot 2 \cdot 2} = ? $$

anonymous · Answer

2*2*2=8

phi · Answer

yes 

 sqr(8)  can be written as sqr(2*2*2)= sqr(2*2) * sqr(2)

igreen · Answer

Right. so going with what @phi just said, you will end up with $2 \sqrt 2$.