Unit Circle
From Wikipedia, the free encyclopedia
Illustration of a unit circle. The variable t is an angle measure.
In mathematics, a unit circle is a circle with a radius of one. Frequently, especially in trigonometry, “the” unit circle is the circle of radius one centered at the origin (0, 0) in the Cartesian coordinate system in the Euclidean plane. The unit circle is often denoted S^{1}; the generalization to higher dimensions is the unit sphere.
If (x, y) is a point on the unit circle in the first quadrant, then x and y are the lengths of the legs of a right triangle whose hypotenuse has length 1. Thus, by the Pythagorean theorem, x and y satisfy the equation
 x^{2} + y^{2} = 1.
Since x^{2} = (−x)^{2} for all x, and since the reflection of any point on the unit circle about the x or yaxis is also on the unit circle, the above equation holds for all points (x, y) on the unit circle, not just those in the first quadrant.
One may also use other notions of “distance” to define other “unit circles”, such as the Riemannian circle; see the article on mathematical norms for additional examples.
Tag Archives: MTH 201
Timetable for: 2010/01/04 to 2010/04/25


Monday  Tuesday  Wednesday  Thursday  Friday  

8:00    SHP201B ******* JW108A 
SHP201B ******* JW108A 
SHP201B ******* JW108A 
  
8:55    SHP201B ******* JW108A 
SHP201B ******* JW108A 
SHP201B ******* JW108A 
  
9:50    SHP201B ******* JW108A 
SHP201B ******* JW108A 
SHP201B ******* JW108A 
  
10:45    SHP201B ******* JW108A 
SHP201B ******* JW108A 
SHP201B ******* JW108A 
  
11:40    SHP201B ******* JW108A 
THY201AB ******* JW205 
CUL255AB ******* JW205 
  
12:35  CUL255AB ******* JW205 
TLD201AB ******* JW205 
THY201AB ******* JW205 
THY201AB ******* JW205 
  
13:30  CUL255AB ******* JW205 
TLD201AB ******* JW205 
      
14:25  CAM201B ******* JW203 
        
15:20  CAM201B ******* JW203 
        
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23 HOURS per week 