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5 results for “subtraction”

Formulae (3)

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

Angle subtraction formula for sine.

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

Angle subtraction formula for cosine.

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

Angle subtraction formula for tangent.

Subtract each digit from 9 except the last, which you subtract from 10. Works for any power of 10.

a² − b² = (a + b)(a − b). Turns a subtraction of squares into an easy product.