Radio Shack TRS-80

repeat the process
until
you
find
the right
tree
...
or
surrender
to
frostbite. Or
you
can use
a little trigonometry.
Trigonometry will let
you
figure
the height,
H,
of
the
tree
from two
simple
facts:
your
distance, D, from the
base
of
the tree,
and the angle,
A,
between the base and
tip
of the
tree as measured from
the
point at which
you're
standing:
If you're
standing
as indicated in the
drawing, then
H
=
D*TAN(A)
(That's
"H equals D times the
tangent of angle
A.")
Here's where
the
TRS-80 comes
in.
(You'll also
need
a very long
extension
cord
to run from
the nearest
electrical
outlet
to
the
site of the
tree.)
TAN(X)
is one of
the trigonometric
functions
available
as a subroutine
for
the
TRS-80.
Turn
to page
218
of
Appendix
A and find the
Tangent
Subroutine.
(It's
the
longest
of
the
"trig"
subroutines,
because
it actually contains
two of the
others, Sine
and
Cosine).
Type NEW to clear
out the
program
memory and
carefully
type in
the
tangent
subroutine
(steps
30300
to
30455).
Be sure to add a protective END
block:
30000
END
Now
type in the
following
program:
1
tar
IN.
"HOW FAR ARE
YOU FROM BASE OF
TREE";D
20
IN.
"WHAT IS
ANGLE BETWEEN TIP
AND
BASE OF TREE";A
30 X=A:GOSUB
30320
40 H=INT(
D*Y+
.5
)
50 IF
H=28 THEN
80
60 P.
"FIND
ANOTHER
TREE
—
THIS ONE
IS"sH;
"FEETTALL."
?A
,!»,
161