Casio 3950P, Programming Manual

Page: 27 / 48

25
16 Finding the angles in a triangle
Law of cosines
：
The relationship between the length
of the sides of a triangle and the angle between is
given by:
Solving this for we obtain the angle in terms of the
lengths:
Program
？→ Ａ：？→ Ｂ：？→ Ｃ：ＣＯＳ
－１
（ （Ｂ
２
＋ Ｃ
２
－ Ａ
２
）÷２ ＢＣ）→ Ｄ：Ｄ ＜
33 STEP
＞
Execution Example:
Find the angle in a triangle with sides of length 3, 4 and 5.
To obtain the answer in radians press before
executing the program.
a
2
b
2
c
2
2 bc
θ
cos – + =
a
b
c
θ
θ
1 –
cos
b
2
c
2
a
2
– +
2 bc
----------------------------- =
ON MODE MODE MODE 1
PRGM
MODE 1
COMP
1
P1
MODE MODE
MODE MODE 1
DEG
S A D R P1 P1 P2 P3 P4 G
Prog 1
5
EXE
S A D R P1 P1 P2 P3 P4 G
4 EXE S A D R P1 P1 P2 P3 P4 G
3 EXE S A D R P1 P1 P2 P3 P4 G
8
MODE MODE MODE MODE
2
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