Texas Instruments TI-89 Titanium Short User Manual page 119

When converted to rectangular form, the sum
of vectors i and c equals the resultant vector r.
4. Using function
r to rectangular form.
Enter:
!
p2r(i) i
!
p2r(c) c
!
p2r(r) r
Because the vectors are equal, the x-coordinate
of i+c must equal the x-coordinate of the
resultant vector r. Likewise, the y-coordinate of
i+c must equal the y-coordinate of resultant
vector r.
5. Set up two equations involving vectors i+c
and r.
• Equation 1 sets the x-coordinates equal
to each other.
• Equation 2 sets the y-coordinates equal.
Store these equations into eq1 and eq2,
respectively. Enter:
i[1,1]+c[1,1]=r[1,1]
i[1,2]+c[1,2]=r[1,2]
6. Solve eq2 for b to calculate the actual
speed of the boat.
solve(eq2,b)
7. Substitute the known value of b into eq1,
and solve eq1 for a to determine a, the
speed of the eastward traveling current.
solve(eq1,a) | b
The boat travels at a speed of 22.7 knots, and
the water current is approximately 7.9 knots.
Activities
, convert vectors i, c, and
p2r
!
eq1
!
eq2
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