I sin 2 x + cos 2 x ::= sinxsiny :::: H cos (x - y) - cos (x + y) cos 2x = cos 2 x - sin 2 x cos x cos y = H cos ( x + y) +' cos (x - y) = 2 cos 2 x - 1 sinxcosy = Hsin(x+y)+sin(x-y) = 1 - 2 sin 2X cosxsiny ::= = ± Vl- cos 2 x = 1 - sin 2x cos x = ±-Vl tan x = sin x cot x cos x ' cos 2 x sin 2 x 1 sec x sin x ' = ::= cos x sin x IHALFARCI 1 cos x 1 tan x tn.: = + cot 2 x !Sin x = lSin x ::= 1 ::= csc 2 x ::: sec 2 x { + 1 I ADDITIoN I· ~ cox X == ::= 1 - = 2 cos(x; cos 2x 2 cos x + cos ± V l - ~os 2x sinx+siny = 2 sin(x;Y)cos(x;2Y) sin x - sin y COS 2 X ![sin(x+y)-sin(x-y) 2 tan x == 1 - tan 2x tan 2x 2 sin 2 x + cos 2 x I 2 sin x cos x sin x = , PRODUCT ::= -cos 2x cot x I sin 2x =1 = ARC 1 sin 2 x csc x [OOWtE FUNDAMENTAL) Y= Y} sin(x 2y) 2 cos(x; y) cos(x;2 cos x - cos y = -2 sin (~) sin (Y) 1 + cos2x 2 ± V l + cos 2x tan x sin 2x = 1 + cos 2x tan x _ 1 - cos 2x sin 2x REDUCTION OF AcosO + BsinO For the diagram below, a (A,B) = VA2 tan( x ± y) = + sin tan x ±tan y 1 tan x tan y + x sin y + B A = a cos 4> B = asinql sin (x ± y) = sin x cos y ± cos x sin y cos(x± y) = cos x cos y Y) For all values of a, Acose + Bsina· = a cos(a - 4»