Math things and js

Question

I’m not really good at math involving circles, so I honestly have no idea how to do this

How would you find the 2 y positions on a circle with x?

the center of the circle is on (0,0)
And the radius is 5

so if your at x = 2 or something, how could you find the y positions?

Answer 1

y=+-✓21

Here is how:
The general equation is
{(x - a)^2} + {(y - b)^2} = {r^2}
In your case a=b=0, r^2=25
{x ^2} + {y ^2} = 25

Plug in x= 2 and you'll get:
y^2=25-x^2
y^2=21
y=+-✓21

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You can try doing it with x=4, answer should be y=+-3