# Atan2 Method

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

**Namespace:**System

**Assembly:**mscorlib (in mscorlib.dll)

#### Parameters

- y
- Type: System..::..Double

The y coordinate of a point.

- x
- Type: System..::..Double

The x coordinate of a point.

#### Return Value

Type: System..::..DoubleAn angle, θ, measured in radians, such that -π ≤ θ ≤ π, 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 < θ ≤ π.

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

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

If y is 0 and x is not negative, θ = 0.

If y is 0 and x is negative, θ = π.

If y is positive and x is 0, θ = π/2.

If y is negative and x is 0, θ = -π/2.

- Full trust for the immediate caller. This member cannot be used by partially trusted code. For more information, see dd66cd4c-b087-415f-9c3e-94e3a1835f74.

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