Home
Random
Log in
Settings
Donate
About Wikiversity
Disclaimers
Search
Đẳng thức tổng 2 góc
Language
Watch
Edit
sin
(
x
+
y
)
=
sin
(
x
)
cos
(
y
)
+
cos
(
x
)
sin
(
y
)
{\displaystyle \sin(x+y)=\sin(x)\cos(y)+\cos(x)\sin(y)}
sin
(
x
−
y
)
=
sin
(
x
)
cos
(
y
)
−
cos
(
x
)
sin
(
y
)
{\displaystyle \sin(x-y)=\sin(x)\cos(y)-\cos(x)\sin(y)}
cos
(
x
+
y
)
=
cos
(
x
)
cos
(
y
)
−
sin
(
x
)
sin
(
y
)
{\displaystyle \cos(x+y)=\cos(x)\cos(y)-\sin(x)\sin(y)}
cos
(
x
−
y
)
=
cos
(
x
)
cos
(
y
)
+
sin
(
x
)
sin
(
y
)
{\displaystyle \cos(x-y)=\cos(x)\cos(y)+\sin(x)\sin(y)}
sin
(
x
)
+
sin
(
y
)
=
2
sin
(
x
+
y
2
)
cos
(
x
−
y
2
)
{\displaystyle \sin(x)+\sin(y)=2\sin \left({\frac {x+y}{2}}\right)\cos \left({\frac {x-y}{2}}\right)}
sin
(
x
)
−
sin
(
y
)
=
2
cos
(
x
+
y
2
)
sin
(
x
−
y
2
)
{\displaystyle \sin(x)-\sin(y)=2\cos \left({\frac {x+y}{2}}\right)\sin \left({\frac {x-y}{2}}\right)}
cos
(
x
)
+
cos
(
y
)
=
2
cos
(
x
+
y
2
)
cos
(
x
−
y
2
)
{\displaystyle \cos(x)+\cos(y)=2\cos \left({\frac {x+y}{2}}\right)\cos \left({\frac {x-y}{2}}\right)}
cos
(
x
)
−
cos
(
y
)
=
−
2
sin
(
x
+
y
2
)
sin
(
x
−
y
2
)
{\displaystyle \cos(x)-\cos(y)=-2\sin \left({\frac {x+y}{2}}\right)\sin \left({\frac {x-y}{2}}\right)}
tan
(
x
)
+
tan
(
y
)
=
sin
(
x
+
y
)
cos
(
x
)
cos
(
y
)
{\displaystyle \tan(x)+\tan(y)={\frac {\sin(x+y)}{\cos(x)\cos(y)}}}
tan
(
x
)
−
tan
(
y
)
=
sin
(
x
−
y
)
cos
(
x
)
cos
(
y
)
{\displaystyle \tan(x)-\tan(y)={\frac {\sin(x-y)}{\cos(x)\cos(y)}}}
cot
(
x
)
+
cot
(
y
)
=
sin
(
x
+
y
)
sin
(
x
)
sin
(
y
)
{\displaystyle \cot(x)+\cot(y)={\frac {\sin(x+y)}{\sin(x)\sin(y)}}}
cot
(
x
)
−
cot
(
y
)
=
−
sin
(
x
−
y
)
sin
(
x
)
sin
(
y
)
{\displaystyle \cot(x)-\cot(y)={\frac {-\sin(x-y)}{\sin(x)\sin(y)}}}
