Hour of Math · SS2 · Unit FMP17

Compound Angles

Derive the compound-angle formulas for sin(A+-B), cos(A+-B) and tan(A+-B) from the unit-circle chord, use them for exact values at 15/75/105 degrees, apply them to numeric ratios with the sign fixed by the quadrant, and recognise an expression as a disguised compound-angle formula.

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