HP HP-21 - Page 46

To use the , B and functions, key in the number and
press the appropriate function key. To use the arc functions,
press I then press the associated function key. Forexample,
find (.866):
Press Display
.866
I
(=]
degrees
depending
upon
or
which angular mode
radians you are in.
Trigonometric functions can be performed in either of two
angular modes: decimal degrees or decimal radians. Note
that trigonometric functions assume decimal angles regardless
of angular mode. To select a mode, use the o [[[[Mllr~ slide
switch.
Example 1: Find the cosine of 35°. If the HP-21 is not already
in Degrees mode, switch to o [[[[Ill~ before performing the
calculation.
Solution:
35
Example 2: Find the tangent of 6 radians.
Solution:
Switch oec ] r0
6 X
Example 3: In the midst of his transpacific crossing, bronzed
surfer
Ishmael
Queequeg
begins
to
tire,
and
he
decides
to
paddle
his board for either Honolulu, Hawaii (21° 18’ N, 157° 52’ W),
or Anchorage, Alaska (61° 13’ N, 149° 54’ W). Queequeg knows
his own position (45° 37’ N, 150° 12’ W), and he knows that the
great circle distance between two points is given by the formula
Distance = cos™! [sin(LAT,) sin(LAT,) +
cos(LAT,) cos(LAT,) cos(LNG4—LNG,)]| x 60.
Where LAT, and LNG;, = latitude and longitude of the
source (Queequeg).
LAT, and LNG, = latitude and longitude of the
destination.
Which port will be closer for Queequeg and his surfboard?