The center of a circle is at the origin. An endpoint of a diameter of the circle is at (-3, -4). How long is the diameter of the circle?

Question

anonymous · Answer

Find the distance from the origin to the point and double it.

Hint: a very common right triangle has sides of length 3, 4, and 5.

anonymous · Answer

i got 10??

anonymous · Answer

or is it 5 or 25??

anonymous · Answer

It is 10.  Since the horizontal distance is 3 and the vertical distance is 4, the hypotenuse (the distance frmo the origin to the point) is 5.  That is the radius, so the diameter is 10.

anonymous · Answer

thanks

anonymous · Answer

np

anonymous · Answer

mitbender74 that's it. The answer can also be explained as absolute magnitude of a vector (thats sqrt(a^2+b^2)) multiplied by 2 to get from radius diameter

anonymous · Answer

Right.  The magnitude of a vector is essentially the Pythagorean Theorem with an arrowhead :)