Algebra 2/Trigonometry Reference Sheet Area of a Triangle 1 ab sin C K=_ 2 Functions of the Sum of Two Angles Law of Cosines sin (A + B) = sin A cos B + cos A sin B cos (A + B) = cos A cos B – sin A sin B tan A + tan B tan (A + B) = ___________ 1 – tan A tan B sin 2A = 2 sin A cos A cos 2A = cos2 A – sin2 A cos 2A = 2 cos2 A – 1 cos 2A = 1 – 2 sin2 A Functions of the Difference of Two Angles 2 tan A tan 2A = _______ 1 – tan2 A a 2 = b 2 + c 2 – 2bc cos A Functions of the Double Angle sin (A – B) = sin A cos B – cos A sin B cos (A – B) = cos A cos B + sin A sin B tan A – tan B tan (A – B) = ____________ 1 + tan A tan B Functions of the Half Angle _________ sin _1 2 Law of Sines b = ____ c a = ____ ____ sin A sin B sin C _________ 1 – cos A tan A = ± _______ 1 + cos A 1 _ 2 Sum of a Finite Geometric Series a 1(1 – r n) _______ Sn = 1–r Binomial Theorem (a + b)n = nC0anb0 + nC1an – 1b1 + nC2an – 2b2 + ... + nCna0bn n (a + = ∑ n – rbr nC r a r=0 Algebra 2/Trigonometry Sampler – Fall ’09 _________ + cos A cos _1 A = ± 1_______ 2 2 Sum of a Finite Arithmetic Series n(a1 + an) Sn = _______ 2 b)n √ √ √ – cos A A = ± 1_______ 2 [21]