A person in a rowboat two miles from the nearest point on a straight shoreline wishes to reach a house six miles farther down th
e shore. if the person can row at a rate of 3 mi/h and walk at a rate of 5 mi/h, find the least amount of time required to reach the house. how far from the house should the person land the rowboat?
1 answer:
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Answer: cos(Θ) = (√15) / 4
Explanation:
The question states:
1) sin(Θ) = 1/4
2) 0 < Θ < π / 2
3) find cos(Θ)
This is how you solve it.
1) Use the fundamental identity (in this part I use α instead of Θ, just for facility of wirting the symbols, but they mean the same for the case).
2) From which you can find:
3) Replace sin(α) with 1/4
=>
=>
4) Given that the angle is in the first quadrant, you know that cosine is positive and the final answer is:
cos(Θ) =
.
And that is the answer.
Explanation:
The question states:
1) sin(Θ) = 1/4
2) 0 < Θ < π / 2
3) find cos(Θ)
This is how you solve it.
1) Use the fundamental identity (in this part I use α instead of Θ, just for facility of wirting the symbols, but they mean the same for the case).
2) From which you can find:
3) Replace sin(α) with 1/4
=>
=>
4) Given that the angle is in the first quadrant, you know that cosine is positive and the final answer is:
cos(Θ) =
And that is the answer.