cos A = Adjacent side/Hypotenuse = AC/AB tan A = Opposite side/Adjacent side = BC/AC We can derive some other sin cos tan formulas using these definitions of sin, cos, and tan functions. We know that sin, cos, and tan are the reciprocals
The Law of Cosines says: c2 = a2 + b2 − 2ab cos (C) Put in the values we know: c2 = 82 + 112 − 2 × 8 × 11 × cos (37º) Do some calculations: c2 = 64 + 121 − 176 × 0.798. More calculations: c2
0. Cos 360°. 1. cos 2 (α) + sin 2 (α) = 1. cos α = 1/sec α. cos (−α) = cos (α) arccos (cos (α)) = α + 2kα [where k=integer] Cos (2α) = cos 2 (α) − sin 2 (α) cos (α) =