The Radius Of The Inscribed Circle - Casio fx-3650P Programming Manual

17

The radius of the Inscribed circle.

The inscribed circle is shown in the diagram on the
right.When the inscribed circle has radius
the appropriate triangle is:
AR BR
S = ----- - + ----- - +
2 2
Now, using herons formula it is possible to determine
the area of the triangle in terms of the length of the
three sides, whereby the radius of the circle is:
(
D D A
–
R = ----------------------------------------------------------
ON MODE MODE
？→ Ａ：？→ Ｂ：？→ Ｃ： （Ａ ＋ Ｂ ＋ Ｃ）÷２→ Ｄ：√（Ｄ（Ｄ － Ａ） （Ｄ － Ｂ） （Ｄ － Ｃ） ）
÷ Ｄ → Ｍ：Ｍ ＜ 49 STEP ＞
OUTPUT Ｍ : the radius of the inscribed circle
For a triangle with sides of length 3, 4 and 5, the radius of the inscribed circle is 1:
Prog 1
EXE
3
4 EXE
EXE
5
26
( )
CR A B C + +
----- - = -----------------------------
2 2
) ( ) ( )
D B D C
– –
,
D
MODE
R
, the area of
R
A B C
+ +
D = ---------------------
2
PRGM
COMP
1 MODE
S A
S A
S A
S A M
A
R
C
1 1
P1 P1 P2 P3 P4 D R
P1 P1 P2 P3 P4 D R
P1 P1 P2 P3 P4 D R
P1 P1 P2 P3 P4 D R
B
G
G
G
G