Chapter 7: Small Angles & Approximation
Now, cos
q
= 1
-
2 sin
2
½
q
»
1
-
2(½
q
)
2
, if
q
is small
»
1
-
½
q
2
Þ
For small
Ð
q
,
cos
q
»
1
-
½
q
2
.
Also, tan
q
sin
q
=
¾¾
cos
q
q
»
¾¾¾
1
-
½
q
2
=
q
(1
-
½
q
2
)
-
1
=
q
[1 + (
-
1)(½
q
2
) +
¼
]
=
q
+ ½
q
3
+
¼
Þ
For small
Ð
q
,
tan
q
»
q
.
Index
