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  2. atan2 - Wikipedia

    en.wikipedia.org/wiki/Atan2

    atan2(y, x) returns the angle θ between the positive x-axis and the ray from the origin to the point (x, y), confined to (−π, π].Graph of ⁡ (,) over /. In computing and mathematics, the function atan2 is the 2-argument arctangent.

  3. Normal curve equivalent - Wikipedia

    en.wikipedia.org/wiki/Normal_curve_equivalent

    where z is the standard score or "z-score", i.e. z is how many standard deviations above the mean the raw score is (z is negative if the raw score is below the mean). The reason for the choice of the number 21.06 is to bring about the following result: If the scores are normally distributed (i.e. they follow the "bell-shaped curve") then

  4. Score test - Wikipedia

    en.wikipedia.org/wiki/Score_test

    In many situations, the score statistic reduces to another commonly used statistic. [11] In linear regression, the Lagrange multiplier test can be expressed as a function of the F-test. [12] When the data follows a normal distribution, the score statistic is the same as the t statistic. [clarification needed]

  5. List of trigonometric identities - Wikipedia

    en.wikipedia.org/wiki/List_of_trigonometric...

    A formula for computing the trigonometric identities for the one-third angle exists, but it requires finding the zeroes of the cubic equation 4x 3 − 3x + d = 0, where is the value of the cosine function at the one-third angle and d is the known value of the cosine function at the full angle.

  6. Inverse tangent integral - Wikipedia

    en.wikipedia.org/wiki/Inverse_tangent_integral

    The inverse tangent integral is defined by: ⁡ = ⁡ The arctangent is taken to be the principal branch; that is, − π /2 < arctan(t) < π /2 for all real t. [1]Its power series representation is

  7. Inverse trigonometric functions - Wikipedia

    en.wikipedia.org/wiki/Inverse_trigonometric...

    The most common convention is to name inverse trigonometric functions using an arc- prefix: arcsin(x), arccos(x), arctan(x), etc. [1] (This convention is used throughout this article.) This notation arises from the following geometric relationships: [ citation needed ] when measuring in radians, an angle of θ radians will correspond to an arc ...

  8. 'It's disappointing to all of us': RICAS state results are ...

    www.aol.com/disappointing-us-ricas-state-results...

    The drop in English scores disappointed state education officials.

  9. Z-test - Wikipedia

    en.wikipedia.org/wiki/Z-test

    Difference between Z-test and t-test: Z-test is used when sample size is large (n>50), or the population variance is known. t-test is used when sample size is small (n<50) and population variance is unknown. There is no universal constant at which the sample size is generally considered large enough to justify use of the plug-in test.