27
18
The radius of the Circumscribed circle
The law of sines
：
For
△
ABC
, as shown in the
diagram on the right, the following formula holds:
It is thereby possible, by the law of cosines and law of
sines, to calculate the radius of the circumscribed
circle given the lengths of the three sides of the
triangle.
Program
？→ Ａ：？→ Ｂ：？→ Ｃ：ｓｉｎ ｃｏｓ
－１
（
（Ｂ
２
＋ Ｃ
２
－ Ａ
２
）÷２ ＢＣ）→ Ｄ：
Ａ ÷２ Ｄ → Ｍ：Ｍ ＜
41 STEP
＞
OUTPUT
Ｍ
: the radius of the circumscribed circle
Execution Example:
For a triangle with sides if length 3, 4 and 5, the radius of the circumscribed circle is 2.5:
a
A
sin
-----------
b
B
sin
-----------
c
C
sin
-----------
2
R
=
=
=
A
B
a
c
b
C
R
R
A
2
1
–
cos
B
2
C
2
A
2
–
+
2BC
-------------------------------
sin
-------------------------------------------------------------
=
ON
MODE
MODE
MODE
1
PRGM
MODE
1
COMP
1
P1
Prog
1
S A
D R
P1
P1 P2 P3 P4
G
3
EXE
S A
D R
P1
P1 P2 P3 P4
G
4
EXE
S A
D R
P1
P1 P2 P3 P4
G
888888888
88
8 8 8 8 8 8 8 8 8 8
5
EXE
M
S A
D R
P1
P1 P2 P3 P4
G
関数電卓事例集
.book 27
ページ
２００２年９月２日 月曜日 午後６時５１分
Summary of Contents for 3950P
Page 1: ......
Page 46: ...MEMO MEMO MEMO MEMO...
Page 47: ...Authors Dr Yuichi Takeda Research and Development Initiative Chuo University...
Page 48: ......
