Calculates the reference angle for a given angle. Also known as the positive acute angle.

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- Quadrant 1 = θ
- Quadrant 2 = 180 -θ
- Quadrant 3 = θ - 180
- Quadrant 4 = 360 - θ

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- angle
- the figure formed by two rays, called the sides of the angle, sharing a common endpoint, called the vertex of the angle.
- cos
- cos(θ) is the ratio of the adjacent side of angle θ to the hypotenuse
- cot
- The length of the adjacent side divided by the length of the side opposite the angle. Also equals 1/tan(θ)
- csc
- the length of the hypotenuse divided by the length of the adjacent side. Also equals 1/sin(θ)
- gradian
- defined as one hundredth of the right angle. This is equal to π/200 or 9/10°
- radian
- a unit of plane angular measurement that is equal to the angle at the center of a circle subtended by an arc whose length equals the radius or approximately 180°/π ~ 57.3 degrees.
- reference angle
- the smallest possible angle made by the terminal side of the given angle with the x-axis.
- sec
- the length of the hypotenuse divided by the length of the adjacent side. Also equals 1/cos(θ)
- sin
- sin(θ) is the ratio of the opposite side of angle θ to the hypotenuse
- tan
- the ratio of the opposite side to the adjacent side of a particular angle of the right triangle.