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11 results for “Addition”

Formulae (9)

\frac{a}{b} + \frac{c}{d} = \frac{ad + bc}{bd}

Add two fractions using a common denominator.

\sin(A \pm B) = \sin A\cos B \pm \cos A\sin B

Angle addition formula for sine.

\cos(A \pm B) = \cos A\cos B \mp \sin A\sin B

Angle addition formula for cosine.

\sin(A+B) = \sin A\cos B + \cos A\sin B

Angle addition formula for sine.

\cos(A+B) = \cos A\cos B - \sin A\sin B

Angle addition formula for cosine.

\tan(A+B) = \frac{\tan A + \tan B}{1 - \tan A\tan B}

Angle addition formula for tangent.

P(A \cup B) = P(A) + P(B) - P(A \cap B)

Probability that A or B occurs.

(A+B)_{ij} = a_{ij} + b_{ij}

Matrices of equal size add entry by entry.

MR = \dfrac{\Delta TR}{\Delta Q}

Marginal revenue is the extra revenue earned from selling one additional unit.

A quick way to verify multiplication and addition results by checking digit sums modulo 9.

Add the big place values first (left to right) instead of the traditional right-to-left carrying — easier to hold in your head.