SOLUTION: A cruise ship sailed north for 50 km. Then, the captain turned the ship eastward through an angle of pi/6 and sailed an additional 50 km. Without using a calculator, determine an e

Algebra ->  Trigonometry-basics -> SOLUTION: A cruise ship sailed north for 50 km. Then, the captain turned the ship eastward through an angle of pi/6 and sailed an additional 50 km. Without using a calculator, determine an e      Log On


   



Question 617271: A cruise ship sailed north for 50 km. Then, the captain turned the ship eastward through an angle of pi/6 and sailed an additional 50 km. Without using a calculator, determine an exact expression for the direct distance from the start to the finish of the cruise.
Answer by nerdybill(7384) About Me  (Show Source):
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A cruise ship sailed north for 50 km. Then, the captain turned the ship eastward through an angle of pi/6 and sailed an additional 50 km. Without using a calculator, determine an exact expression for the direct distance from the start to the finish of the cruise.
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π/6 = 30 deg = turn from north towards the east.
supplementary angle (inside triangle formed) = (180 - 30) = 150 deg
.
This forms a 50 Km, 50 Km, side_c triangle with the angle between the
two 50 Km sides = 150 deg.
.
use the law of cosines: where C = 150 deg
.
c² = a² + b² − 2abcos[C]
c² = (50)² + (50)² − 2(50)(50)cos[150] ... cos[150] = (-√3)/2
c² = 5000 + 2500(√3)
c%5E2+=+a%5E2+%2B+b%5E2+-+2ab%2Acos%28C%29
c%5E2+=+50%5E2+%2B+50%5E2+-+2%2A50%2A50%2Acos%28pi%2F6%29
c%5E2+=+2500+%2B+2500+-+100%2A50%2A%28-sqrt%283%29%2F2%29
c%5E2+=+5000+-+5000%2A%28-sqrt%283%29%2F2%29
c%5E2+=+5000+%2B+5000%2A%28sqrt%283%29%2F2%29
c%5E2+=+5000+%2B+2500%2Asqrt%283%29
c+=+sqrt%285000+%2B+2500%2Asqrt%283%29%29