Coordinates of a point on circle

[jimmykk]

I have a general question regarding finding the coordinates of a point at circle.
Center of circle is 0,0. Radius of circle is 8.5mm. First point on circle boundary is 8.5,0.
I want to find the coordinates of a second point on the circle boundary that is 2.5mm away from this 8.5, 0 point.

 

[KlausST]

Hi,

I won't do your homework ... just give hints.

In a drawing you'd draw a circle wit radius of 2.5mm around (8.5 / 0) point.

Mathematically do it the same way
You have two circles, one with radius of 8.5 mm around (0 / 0)
The other circle with 2.5mm around (8.5 / 0).
Set up the formulas for both circles and and find the crossing (by setting them equal). Two points.

2) another option is via pythagoras.
The resulting triangle is symmetric. Thus if you divide it into two halves you get two triangles with right angle.

Klaus

 

[betwixt]

and consider that you know the circumference, work out want proportion of it 2.5mm of it must be and convert back to the coordinate.

Brian.