TRIGNOMETRY IDENTITIES

Trigonometry (trig) identities

A. Reciprocal identities

a1	sin  A = 1  csc  A	a4	csc  A = 1  sin  A
a2	cos  A = 1  sec  A	a5	sec  A = 1  cos  A
a3	tan  A = 1  cot  A	a6	cot  A = 1  tan  A

B. Ratio identities

b1	tan  A =  sin  A  cos  A
b2	cot  A =  cos  A  sin  A

C. Opposite Angle identities

c1	sin  ( − A ) = −  sin  A
c2	cos  ( − A ) = c o s A  (Caution - not like c1, c3)
c3	tan  ( − A ) = −  tan  A

D. Complementary angle identities

e1	sin  A =  cos  π 2 − A
e2	tan  A =  cot  π 2 − A
e3	sec  A =  csc  π 2 − A