You may find some of the following formulas useful: sin (A) + cos (A

You may find some of the following formulas useful:
sin2 (A) + cos2 (A) = 1
tan2 (A) + 1 = sec2 (A)
1 + cot2 (A) = csc2 (A)
sin(A + B) = sin (A) cos (B) + cos (A) sin (B)
sin(A − B) = sin (A) cos (B) − cos (A) sin (B)
cos(A + B) = cos (A) cos (B) − sin (A) sin (B)
cos(A − B) = cos (A) cos (B) + sin (A) sin (B)
sin (2A) = 2 sin (A) cos (A)
cos (2A) = cos2 (A) − sin2 (A)
cos (2A) = 1 − 2 sin2 (A)
cos (2A) = 2 cos2 (A) − 1
sin2 (A/2) =
1 − cos (A)
2
cos2 (A/2) =
1 + cos (A)
2
sin (A) sin (B) sin (C)
=
=
a
b
c
c2 = a2 + b2 − 2ab cos (C)
x=
−b ±
√
b2 − 4ac
2a
an = a + (n − 1)d
Sn = n
(a1 + an )
2
an = arn−1
Sn =
n[2a + (n − 1)d]
2
Sn =
a(1 − rn )
1−r