A fence 6 feet tall runs parallel to a tall building at a distance of 6 feet from the building. We want to find the the length o
f the shortest ladder that will reach from the ground over the fence to the wall of the building. Here are some hints for finding a solution: Use the angle that the ladder makes with the ground to define the position of the ladder and draw a picture of the ladder leaning against the wall of the building and just touching the top of the fence. If the ladder makes an angle 0.82 radians with the ground, touches the top of the fence and just reaches the wall, calculate the distance along the ladder from the ground to the top of the fence. equation editorEquation Editor The distance along the ladder from the top of the fence to the wall is equation editorEquation Editor Using these hints write a function L(x) which gives the total length of a ladder which touches the ground at an angle x, touches the top of the fence and just reaches the wall. L(x) = equation editorEquation Editor . Use this function to find the length of the shortest ladder which will clear the fence. The length of the shortest ladder is equation editorEquation Editor feet.
1 answer:
Answer:
12√2 feet ≈ 16.97 feet
Step-by-step explanation:
For the dimensions shown in the attached diagram, the distance "a" along the ladder from the ground to the fence is ...
a = (6 ft)/sin(x) = (6 ft)/sin(0.82) ≈ 8.206 ft
The distance along the ladder from the top of the fence to the wall is ...
b = (6 ft)/cos(x) = (6 ft)/cos(0.82) ≈ 8.795 ft
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In general, the distance along the ladder from the ground to the wall is ...
L(x) = a +b
L(x) = 6/sin(x) +6/cos(x)
This distance will be shortest for the case where the derivative with respect to x is zero.
L'(x) = 6(-cos(x)/sin(x)² +sin(x)/cos(x)²) = 6(sin(x)³ -cos(x)³)/(sin(x)²cos(x²))
This will be zero when the numerator is zero:
0 = 6(sin(x) -cos(x))(1 -sin(x)cos(x))
The last factor is always positive, so the solution here is ...
sin(x) = cos(x) ⇒ x = π/4
And the length of the shortest ladder is ...
L(π/4) = 6√2 + 6√2
L(π/4) = 12√2 . . . . feet
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The ladder length for the "trial" angle of 0.82 radians was ...
8.206 +8.795 = 17.001 . . . ft
The actual shortest ladder is ...
12√2 = 16.971 . . . feet
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Answer: Probability that students who did not attend the class on Fridays given that they passed the course is 0.043.
Step-by-step explanation:
Since we have given that
Probability that students attend class on Fridays = 70% = 0.7
Probability that who went to class on Fridays would pass the course = 95% = 0.95
Probability that who did not go to class on Fridays would passed the course = 10% = 0.10
Let A be the event students passed the course.
Let E be the event that students attend the class on Fridays.
Let F be the event that students who did not attend the class on Fridays.
Here, P(E) = 0.70 and P(F) = 1-0.70 = 0.30
P(A|E) = 0.95, P(A|F) = 0.10
We need to find the probability that they did not attend on Fridays.
We would use "Bayes theorem":
Hence, probability that students who did not attend the class on Fridays given that they passed the course is 0.043.
Input is the same as the x-term and output is the same as the y-term.
For example, take a look at the image provided with thee table.
Looking at the first box of our table, notice that if we subtract 5 from 1, we get -4 and if we subtract 5 from 2 we get -3 and if we subtract 5 from 3, we get -2. Notice that in each case, we're subtracting 5 from the input to get the output.
I attached a table so you can practice if you'd like to. All you have to do is subtract 5 from each input and you will end up with the output. The first few are done for you. I also provided an answer key in the next image so you can check your work.
The last one might be a little trick. In the input, we have n which is a variable that represents any number. If we want to find the nth term, we simply subtract 5. So we have n - 5.
First image is practice if you'd like and the second is the key.
If you don't want to do it, no worries.
