Chapter 7: Small Angles & Approximation
Example 4
Without using calculator, find an approximate value for tan 61
°
, given
Ö
3 = 1.732
and
1
°
= 0.017
c
, giving your answer to 3 decimal places.
Solution
tan 61
°
=
tan (60
°
+ 1
°
)
=
tan 60
°
+ tan 1
°
¾¾¾¾¾¾¾
1
-
tan 60
°
tan 1
°
=
Ö
3
+ tan 0.017
¾¾¾¾¾¾¾
1
-
Ö
3
tan 0.017
»
1.732 + 0.017
¾¾¾¾¾¾¾
1
-
1.7
32
(0.017)
»
1.749
¾¾¾
0.9705
»
1.802 (3 d.p.)
tan (
A
+
B
) =
tan
A
+ tan
B
¾¾¾¾¾¾
1
-
tan
A
tan
B
Index
