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A ship sails from harbour H on a bearing of084° for 340 km until it reaches point P. Itthen sails on a bearing of 210° for 160 kmuntil it reaches point Q.a Calculate the distance between point Qb On what bearing must the ship sail toreturn directly to the harbour from Q?and the harbour. |
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Answer» Given: Distance from H to P = 340km Distance from P to Q = 160km Ship bearing angle H to P = 84° Then SAILS from P to Q bearing angle = 210° To find: a) Calculate the distance between point Q and the harbor. b) On what bearing must the ship sail to return directly to the harbor from Q? Solution: (b) Angle between 340km and 160km will be ∠HPQ ∠NPQ = 360° - 210° = 150° i.e total angle P - (1) Now ∠NPH = 180° - 84° = 96° - (2) As we can see HN ║ PN and HP is transversal so sum of interior angle is 180°. From (1) and (2) we get ∠HPQ = ∠NPQ - ∠NPH ∠HPQ = 150° - 96° ∠HPQ = 54° (a) To calculate distance between Q and harbor 'H' We will use COSINE formula as we have one angle and two sides of ΔHPQ ∠P = 54° , HP = 340km , PQ = 160km (QH)² = (PH)² + (PQ)² - 2(PH)(PQ)cos∠HPQ (QH)² = (340)² + (160)² - 2(340)(160)cos54° (QH)² = 519904.965 QH = 227.8km ≈ 228km |
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