Math.Atan2 Method

毕业刚到两年,结果连三角函数的性质、定义域、值域,图像等忘得一干二净。可能是在毕业前就已经忘掉了。
今天画个图需要算几个点的坐标。想起了,他但是很多东西都忘了。
折腾了半天才明白了一点儿,呵呵,
我这次用到了 Math.Tan,Math.Atan2 函数,下面把这两个函数在msdn上的解释拷贝到下面供以后方便查找。

Math.Tan Method 
Returns the tangent of the specified angle.

Parameters

a

An angle, measured in radians.

Return Value

The tangent of a. If a is equal to NaN, NegativeInfinity, or PositiveInfinity, this method returns NaN.

The angle, a, must be in radians. Multiply by π/180 to convert degrees to radians.

Math.Atan2 Method 
Returns the angle whose tangent is the quotient of two specified numbers.

Parameters

y 
       The y coordinate of a point.
x
           The x coordinate of a point.

Return Value

An angle, θ, measured in radians, such that -πθπ, and tan(θ) = y / x, where (x, y) is a point in the Cartesian plane. Observe the following:
  • For (x, y) in quadrant 1, 0 < θ < π/2.

  • For (x, y) in quadrant 2, π/2 < θπ.

  • For (x, y) in quadrant 3, -π < θ < -π/2.

  • For (x, y) in quadrant 4, -π/2 < θ < 0.

posted @ 2007-03-14 00:57  轻松  阅读(636)  评论(0编辑  收藏  举报