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Factoring and product formulas
Quadratic equations
Progressions
Trigonometry
Probability theory
Statistics
Circle
Triangles
Quadrangles, polygons
Shape Areas
Solid figures
Equations of geometric shapes
Various
Combinatorics
Vectors
Logarithms
Factoring and product formulas
Quadratic equations
Progressions
Trigonometry
Probability theory
Statistics
Circle
Triangles
Quadrangles, polygons
Shape Areas
Solid figures
Equations of geometric shapes
Various
Combinatorics
Vectors
Logarithms
Math formulas
Trigonometry
Cotangent of double angle
Cotangent of double angle
$$ctg(2\cdot a) = \frac{ctg(a)-tg(a)}{2}$$
Find
a
a
It is known that:
a
=
x
Calculate '
a
'
1
a
A
δ
Δ
1
2
3
+
<-
4
5
6
-
C
7
8
9
*
(
0
.
=
/
)
^
√
'
!
π
,
;
_
x
sin
cos
tg
ctg
log
arc sin
arc cos
arc tg
arc ctg
ln
′
∫
∫_
|
lg
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
t
u
v
w
x
y
z
A
C
P
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
α
β
γ
δ
ε
ζ
η
θ
ι
κ
λ
μ
ν
ξ
ο
π
ρ
σ
τ
υ
φ
χ
ψ
ω
ß
ℏ
Α
Β
Γ
Δ
Ε
Ζ
Η
Θ
Ι
Κ
Λ
Μ
Ν
Ξ
Ο
Ρ
Σ
Τ
Υ
Φ
Χ
Ψ
Ω
Ā
×
