HP -22S Owner's Manual page 118

Example: Law of Sines. You look down from the top of a 5,000-foot
mountain with your telescope and see two large water towers, one behind
the other. When you point the telescope at one tower, the angle from hor-
izontal is 33°. For the other tower, the angle from horizontal is 48°. How
far apart are the towers?
The unknown is side
a
of triangle
ABC.
Angles
A,
B, and C are easily
found:
A
= 48 - 33 = 15°
B = 180 - 48 = 132°
C = 180 - (15
+
132) = 33°
Side
a
can be calculated using the law of sines if we know any other
side. We do, since c sin E=5000, and E=180-132=48°. Therefore,
c=5000+sin 48°.
Keys~
.1
MODES
I
{DG}
5000
[±]
48
(]ffi]
B
Display:
6,728.1636
Description:
Sets Degrees mode.
Calculates side c.
Now, use the law of sines to calculate side a;
a=c
sin A+sin C:
o
15
(]ffi]
[±]
33
(]ffi]
B
1,741.3769+
3,197.3046
118 8: Additional Examples
Calculates side a.