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A boat drops an anchor to the bottom of a lake. The anchor rope makes a 15 degree angle with the boat. The anchor rope is 24 feet long. To the nearest foot how deep is the lake?

 

I drew a diagram and used (sin=opp/hyp) = sin15=opp/24 and got 6.211

 Jun 2, 2014

Best Answer 

 #5
avatar+118667 
+5

Hi Tavi, 

Let's draw a picure for this.    you see, unless you find the other angle, you must use Cos.

 Jun 3, 2014
 #1
avatar+129849 
+5

Note that the rope makes an angle of 15 degrees with  the boat. We are looking for the side that is adjacent to that angle - (the opposite side would tell us how far the end of the rope is from the boat. Consider the rope as the "hypoteneuse"...what relates the adjacent and the hypoteneuse??)

 Jun 2, 2014
 #2
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+5

the cosine, it would be cos15=adj/24 since I am finding the adj side

 Jun 2, 2014
 #3
avatar+28 
+5

my question would be, if the 15 degree angle is between the water level (the boat) and the anchor line, then one Would want to use sine, because one is measuring the distance from anchor to surface, opposite the angle.

 Jun 2, 2014
 #4
avatar+129849 
+5

Yep, cosine...!!! Your set up is correct....

 Jun 3, 2014
 #5
avatar+118667 
+5
Best Answer

Hi Tavi, 

Let's draw a picure for this.    you see, unless you find the other angle, you must use Cos.

Melody Jun 3, 2014

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