Math Is Fun Forum

thanaras

Member

Registered: 2009-06-21

Posts: 1

calculate θ angle

Hello, i have a very silly question but i am kind of rusty in maths lately. So the question is: we have a cyrcle, and we know the radius and the center which is the origin (0,0). We also know a point on the circle, lets say (1,1). We need to calcualate the angle θ. I know that sin θ = opposite/hypotinuse. But how can we calculate the θ angle and not the sin θ. I am using a 3d software that calculates sin and cos.  Thanks a lot in advance.

Avon

Member

Registered: 2007-06-28

Posts: 80

Re: calculate θ angle

Since

the arctangent of y/x does not completely determine the angle.
For this reason, programming languages usually provide the atan2 function.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: calculate θ angle

Hi Jane;

  Could you recreate your full determination of the angle θ? I would like to see it again.

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

MathsIsFun

Administrator

Registered: 2005-01-21

Posts: 7,713

Re: calculate θ angle

[multiple posts deleted due to rudeness and bad language]

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"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

MathsIsFun

Administrator

Registered: 2005-01-21

Posts: 7,713

Re: calculate θ angle

[more posts deleted that continued on same theme]

You guys should show respect for mathysperson who stepped in as the Moderator and asked you to stop.

Let us all consider this an unfortunate episode, and not debate the rights or wrongs, but instead continue in the best traditions of this forum.

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"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman