Precalculus: Sum and Difference Formulas in Trigonometry
Puoi toccare per girare la carta.
I pulsanti di controllo sono stati cambiati in modalità "navigazione".
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Rewrite 15° as 45° - 30°, then use cos(45° - 30°) = cos 45° cos 30° + sin 45° sin 30°.
tan(α - β) = (tan α - tan β) / (1 + tan α tan β)
To express sums or differences of products like cos 40° cos 80° - sin 40° sin 80° as a single cosine of a sum or difference.
By expressing angles as sums or differences of known angles and applying the formulas.
By rewriting expressions as sums or differences of angles to simplify and solve.
sin(α - β) = sin α cos β - cos α sin β
cos(α - β) = cos α cos β + sin α sin β