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April 20, 2014

April 20, 2014

Posted by **Mz. Suzie** on Monday, March 2, 2009 at 2:30pm.

2. Two boats lie on a straight line with the base of a lighthouse. From the top of the lighthouse, 21 meters above water level, it is observed that the angle of depression of the nearest boat is 53 degrees and the angle of depression of the farthers boat is 27 degrees. How far aprt are the boats?

- Precalculus -
**Reiny**, Monday, March 2, 2009 at 2:56pm#1 My diagram has two right angle triangles with a common right angle, the one with the 53 angle embedded within the larger one.

label the distance from the nearer boat to the lighthouse x, label the distance from the farther boat to the lighthouse y

then tan53 = 21/x

x = 21/tan53

and tan 27 = y/21

distance between the two boats = y-x

#1 (similar to #2)

my diagram has the man standing 12 to the left of the statue, A the top, B the bottom, the line to the top makes an angle of 30º and to the bottom of the statue 15º

draw a horizontalline from the "eye" to the statue meeting it at P

use the tangent ratio twice to find AP and BP

height of statue = AP + BP

- Precalculus -
**Mz. Suzie**, Monday, March 2, 2009 at 3:25pmi still am confused on what to do for the second explanation you gave

- Precalculus -
**Reiny**, Monday, March 2, 2009 at 3:47pmok,

draw a triangle ABE with AB a vertical line, that is your statue.

E is to left of the line AB

Join EA and EB

From E draw a line perpendicular to AB to meet AB at P, P is between A and B

EP = 12

angle AEP=30º

angle BEP = 15º

in top triangle:

AP/12 = tan 30

AP = 12tan30 = 6.928

in bottom triangle

BP/12 = tan15

BP = 12tan15 = 3.215

AB = 10.14

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