Question
Instructions for finding a buried treasure include
the following: Go 585.3 paces at 156◦
,
turn to 215◦
and walk 282 paces, then travel
400 paces at 132◦
.
Find the magnitude of the resultant displacement
from the starting point.
What is the direction of the resultant displacement?
Use counterclockwise from due East as
the positive angular direction, between the
limits of −180◦
and +180◦
.
Answer in units of ◦
.
the following: Go 585.3 paces at 156◦
,
turn to 215◦
and walk 282 paces, then travel
400 paces at 132◦
.
Find the magnitude of the resultant displacement
from the starting point.
What is the direction of the resultant displacement?
Use counterclockwise from due East as
the positive angular direction, between the
limits of −180◦
and +180◦
.
Answer in units of ◦
.
Answers
Damon
585.3 paces at 156◦
cos 156 = -.914
sin 156 = .407
x distance = 585.3 *- .914 = - 525
y distance = 585.3 * .407 = + 238
282 at 215
cos 215 = -.819
sin 215 = -.574
x distance = 282 * -.819
y distance = 282 * -.574
400 at 132
cos 132 = - ....
sin 132 = + ...
x ....
y ....
Now add all the x distances X = .....
then Y = .....
figure out what quadrant by X and Y signs
tan (angle from x axis) = y/x
cos 156 = -.914
sin 156 = .407
x distance = 585.3 *- .914 = - 525
y distance = 585.3 * .407 = + 238
282 at 215
cos 215 = -.819
sin 215 = -.574
x distance = 282 * -.819
y distance = 282 * -.574
400 at 132
cos 132 = - ....
sin 132 = + ...
x ....
y ....
Now add all the x distances X = .....
then Y = .....
figure out what quadrant by X and Y signs
tan (angle from x axis) = y/x
scott
find the x and y components of the individual segments , then add
... the sine of the bearing is the x component , the cosine is the y component
(magnitude)^2 = x^2 + y^2
tan(bearing) = x / y
... the sine of the bearing is the x component , the cosine is the y component
(magnitude)^2 = x^2 + y^2
tan(bearing) = x / y
Damon
Scott, cos is x, they are using counterclockwise from east, not compass directions. Bothers me too (teach navigation).
scott
oops ... got x and y reversed
sine is y ... cosine is x
tan(bearing) = y / x
sine is y ... cosine is x
tan(bearing) = y / x
Damon
and sorry, tan bearing = Y/X
we are used to navigating clockwise from north, but this is counterclockwise from east
we are used to navigating clockwise from north, but this is counterclockwise from east
Cam
But what about the second part? The direction?
Damon
As Scott and I both told you
to get the direction take the inverse tangent of Y/X
to get the direction take the inverse tangent of Y/X
Damon
Be careful about the quadrant. If in quadrant 2 for example angle is between 90 and 180