Math question

[EmperorRob]

I haven't used my geometry in a long time. I have a problem but I can't remember how to solve it.

Let's say I have a circle with its center at point 0,0
Now I only want a 45 degree section of that circle centered on y = 0.
What is the formula for determining the x,y points for the endpoints of that circle.


Here is a crude pic of what I'm trying to accomplish.


circle graph

 

[pjyelton]

I believe the X coordinate should be plus/minus sin(22.5)*radius and Y coordinate should be cos(22.5)*radius. This can be figured out by using a right triangle with the sides being the X and Y coordinates and the hypotonuse being the radius of the circle.

 

[TStep]

radius of your circle = r >> r^2 = x^2 + y^2

SOH CAH TOA - remember?

45/2 = 22.5 degrees

SOH = Sin degrees = O/H >> Sin 22.5 = X/r

CAH = Cos degrees = A/H >> Cos 22.5 = Y/r

 

[Grimmett]

Wow its been a long time since I've seen a reference to Chief Sohcahtoa