A ship leaves POrt P and sails 28km away on bearing of 70 degrees to POrt Q. The ship then turns on a bearing of 160 degrees and sails 21km to POrt R. Find angle PQR, calculate the distance PR, Determine the bearing of R from P.

angle PQR = 180 degrees - 160 degrees = 20 degrees

Steve Steve answered
8 years ago

ships sail on headings, not bearings.

Angle PQR is not the angle between the NS line and R. It is the angle between PQ and QR. That is, 70 + 20 = 90 degrees.

So, now we can figure the x-y displacements:

PQ = <28sin70°,28cos70°> = <26.31,9.58>
QR = <21sin20°,-21cos20°> = <7.18,-19.73>

Add them up and you get PR = <33.49,-10.15> = 35.00 at 106.88°

Dp yygg

Explain Bot Explain Bot answered
8 months ago

To calculate the distance PR, we can use the Law of Cosines. In triangle PQR, we have the side lengths PQ = 28km, QR = 21km, and the angle PQR = 20 degrees.

Using the Law of Cosines formula, we have:

PR^2 = PQ^2 + QR^2 - 2(PQ)(QR)cos(PQR)

PR^2 = (28km)^2 + (21km)^2 - 2(28km)(21km)cos(20 degrees)

PR^2 = 784km^2 + 441km^2 - 1176km^2cos(20 degrees)

PR^2 = 1225km^2 - 1176km^2cos(20 degrees)

Now, we can use a calculator to find the value of cos(20 degrees) and substitute it into the equation to find PR^2. Finally, take the square root of PR^2 to find the distance PR.

To determine the bearing of R from P, we need to calculate the angle PRP. Since we already know angle PQR is 20 degrees, we can find angle PRP using the equation:

angle PRP = 180 degrees - angle PQR

Substitute the value of angle PQR (20 degrees) into the equation:

angle PRP = 180 degrees - 20 degrees

angle PRP = 160 degrees

Therefore, the bearing of R from P is 160 degrees.

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