Trig Identities

cos^2(x)+sin^2(x)=

1

1+tan^2(x)=

sec^2(x)

cot^2(x)+1=

csc^2(x)

tan(x)=

sin(x)/cos(x)

cot(x)=

cos(x)/sin(x)

sin(-x)=

-sin(x)

cos(-x)=

cos(x)

tan(-x)=

-tan(x)

csc(-x)=

-csc(x)

sec(-x)=

sec(x)

cot(-x)=

-cot(x)

csc(x)=

1/sin(x)

sec(x)=

1/cos(x)

cot(x)=

1/tan(x)

sin(x)=

1/csc(x)

cos(x)=

1/sec(x)

tan(x)=

1/cot(x)

sin(x)=

cos (pi/2-x)

cos(x)=

sin (pi/2-x)

tan(x)=

cot (pi/2-x)

csc(x)=

sec (pi/2-x)

sec(x)=

csc (pi/2-x)

cot(x)=

tan (pi/2-x)

cos(x+-y)=

cos(x)cos(y) +- sin(x)sin(y)

sin(x+-y)=

sin(x)sin(y)+-cos(x)cos(y)

tan(x+-y)=

tan(x)+-tan(y)/1+-tan(x)tan(y)

sin2(x)=

2sin(x)cos(x)

cos2(x)=

cos^2(x)-sin^2(x)

2cos^2(x)-1

1-2sin^2(x)

tan2(x)=

2tan(x)/1-tan^2(x)

sin^2(x)=

1-cos2(x)/2

cos^2(x)=

1+cos2(x)/2

tan^2(x)=

1-cos2(x)/1+cos2(x)

sin(x/2)=

+-(1-cos(x)/2)^1/2

cos(x/2)=

+-(1+cos(x)/2)^1/2

tan (x/2)=

+-(1-cos(x))^1/2

(1-cos(x)/sin(x))^1/2

sin (x)/1+cos(x)

sinA/a=

sinB/b

sinC/c

Area of a triangle=

1/2 absinC

a^2=

b^2+c^2-2bc cosA

cosA=

b^2+c^2-a^2/2bc

Heron’s Formula Area=

(s(s-a)(s-b)(s-c))^1/2