WOLFRAM

DEMONSTRATIONS
PROJECT
Squares of Sine and Cosine
α
α
2
α
π
/
2

α
1
1
1
2cos
(
α
)
2sin
(
α
)
cos
(
2
α
)
2
cos
2
(
α
)
2
sin
2
(
α
)
This Demonstration shows formulas for the square of sine and cosine (which are also known as halfangle formulas):
2
sin
2
(
α
)
=
1

cos
(
2
α
)
,
2
cos
2
(
α
)
=
1
+
cos
(
2
α
)
.