Sine
sin(x) = y/r = 1/csc(x)
sin(-x) = -sin(x)
sin\2(x)+cos\2(x) = 1
sin(2x) = 2sin(x)cos(x)
sin\2(x) = (1-cos(2x))/2
sin(A+B) = sinA cosB +cosA sinB
sin(A-B)=sinA cosB -cosA sinB
sin(A-Pi/2)=-cosA
sin(A+Pi/2)=cosA
sinA sinB = .5cos(A-B)-.5cos(A+B)
sinA cosB = .5sin(A-B)+.5sin(A+B)
sinA+sinB = 2sin(.5(A+B) cos.5(A-B)
sinA-sinB = 2cos.5(A+B) cos.5(A-B)~
Cosine
cos(x) = x/r = 1/sec(x)
cos(-x) = cos(x)
cos(2x) = cos\2(x)-sin\2(x)
cos\2(x) = (1+cos(2x))/2
cos(A+B) = cosA cosB -sinA sinB
cos(A-B) = cosA cosB +sinA sinB
cos(A-Pi/2) = sinA
cos(A+Pi/2) = -sinA
cosA cosB = .5cos(A-B)+.5cos(A+B)
cosA+cosB = 2cos.5(A+B) cos.5(A-B)
cosA-cosB = -2sin.5(A+B) sin.5(A-B)~
Tangent
tan(x)=y/x=1/cot(x)
tan(A+B) = (tan(A)+tan(B)) / (1-tan(A)tan(B))
tan(A-B) = (tan(A)-tan(B)) / (1+tan(A)tan(B))~
Secant
sec\2(x)=1+tan\2(x)~
Cosecant
csc\2(x)=1+cot\2(x)~
Law of cosines
c\2=a\2+b\2-2ab cos(C)~
Law of sines
sin(A)/a = sin(B)/b = sin(C)/c
Area = .5bc*sin(A) = .5ac*sin(B) = .5ab*sin(C)~
