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