Semaphore signal flags are used to communicate in places such as on aircraft carriers. Each letter is represented by a specific position of the two flags. Each flag is placed vertically, horizontally, or exactly halfway between the vertical and the horizontal.
Letter or Character
Position of Flag in Right Hand
Position of Flag in Left Hand
A
down and right
down
B
right
down
C
up and right
down
D
up
down
E
down
up and left
F
down
left
G
down
down and left
H
right
down and right
I
down and right
up and right
J
up
left
K
down and right
up
L
down and right
up and left
M
down and right
left
N
down and right
down and left
O
right
up and right
P
right
up
Q
right
up and left
R
right
left
S
right
left and down
T
up and right
up
U
up and right
up and left
V
up
down and left
W
up and left
left
X
up and left
down and left
Y
up and right
left
Z
down and left
left
Space
down
down
Add each letter to the table below by looking at the type of angle between the two flags in the signal for that letter. Letters A and L are already placed. The ‘space’ is not a letter. It is used to put a space between words. Assume the angles are between 0\(^{\circ}\) and 180\(^{\circ}\), but can also include 0\(^{\circ}\) and 180\(^{\circ}\).
Angle Type
Letters
Acute
A,
Right
Obtuse
Straight
L,
Here is how we know that the angle for letter A is acute and for letter L is straight:
Letter A
Letter L
When communicating with semaphore signal flags, there are only four different angle measurements between the two flags. What are these angles? Assume the angles are between 0\(^{\circ}\) and 180\(^{\circ}\), but can also include 0\(^{\circ}\) and 180\(^{\circ}\).
Try to communicate a simple message to a friend using your arms as semaphores.
