I need help on a geometry question. I DO NOT want the answer I just need some help, please. What formula do I use and do I need to graph it?
What is the length of a radius of a circle whose center is at the origin and that passes through point (-8,15)?
2006-09-06 09:17:58 · 7 answers · asked by Samantha Jo 3 in Education & Reference ➔ Homework Help
I HAVE to use the distance formula or the midpoint formula or the slope formula. Sorry I left that out.
2006-09-06 11:28:28 · update #1
There is a triangle formed where the hypotenuse is the radius of the circle. Two sides are 8 and 15. Square root of 8 squared plus 15 squared is the radius.
2006-09-06 09:23:56 · answer #1 · answered by Barkley Hound 7 · 0⤊ 1⤋
The trick it to think of the radius as a line on a graph. Forget about the actual circle, just imagine a line going from the origin to the point (-8,15). That line draws the radius of the circle.
So, if you can imagine it in your head, you don't need to graph it. Well, now what is the length of that line?
If the line were to be on a graph, you could draw a triangle using the x and y axis, and the "radius" line being the hypotenuse.
This triangle would be 8 units along the x axis (don't worry about the negative sign, the distance is the same forwards or backwards), and 15 units on the y-axis. Your question becomes, "what is the length of the hypotenuse?"
a^2 + b^2 = c^2
sqrt(8^2 + 15^2)=length of the hypotenuse = length of the radius
I'll let you do the math...
2006-09-06 09:48:45 · answer #2 · answered by Jenelle 3 · 0⤊ 1⤋
Think of the cartesian plane.It is easier if you draw a graph so that the point (-8,15) forms a triangle on the second quadrant of the cartesian plane then use the pythogras theorem to get the hypotenuse length of the triangle formed, which is also the length of the circle in question.If the cicle was passing through a point(4,3),the length of its radius would be=the square root of(4 squared+3squared)=5
2006-09-06 09:31:04 · answer #3 · answered by mesha 1 · 0⤊ 1⤋
if the center is at the origin, and you are looking for the radius, the radius is the hypoteneuse of the triangle formed with points (-8, 15)
-8 being on the x axis will form one side and 15 up the y axis will form the other side.
a^2 + b^2 = c^2
solve for c with a and b 8 and 15
2006-09-06 09:39:51 · answer #4 · answered by Anonymous · 0⤊ 1⤋
you are looking for the hypotenuse of a right triangle with length 8 and height 15.
formula for a right triangle is:
length^2 + height^2 = hypotenuse^2
2006-09-06 09:20:08 · answer #5 · answered by insider_mole 3 · 1⤊ 1⤋
i think you have to use the distance formula, i passsed geometry wih an A if that helps
2006-09-13 13:16:02 · answer #6 · answered by Me♥Manatees 3 · 0⤊ 0⤋
Well, the center is (0,0), right?
Then draw it on a graph and see it is (0,sth)/(sth,0), then you'll have your answer!
2006-09-06 09:22:08 · answer #7 · answered by Mysterious 3 · 0⤊ 1⤋