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question:Given the vectors overrightarrow{m}=(cos 2x, frac{sqrt{3}}{2}sin x frac{1}{2}cos x) and overrightarrow{n}=(1, frac{sqrt{3}}{2}sin x frac{1}{2}cos x), let the function f(x) = overrightarrow{m} cdot overrightarrow{n}. 1. Find the set of values of x for which the function f(x) attains its maximum value. 2. Let A, B, and C be the three internal angles of an acute triangle ABC. If cos B = frac{3}{5} and f(C) = frac{1}{4}, find the value of sin A.

answer:1. The function f(x) is defined as the dot product of overrightarrow{m} and overrightarrow{n}: f(x) = overrightarrow{m} cdot overrightarrow{n} = cos 2x + left(frac{sqrt{3}}{2}sin x - frac{1}{2}cos xright)^2. Expanding the squared term, we get f(x) = cos 2x + frac{3}{4}sin^2 x + frac{1}{4}cos^2 x - frac{sqrt{3}}{2}sin xcos x. Using the double-angle formulae, we can rewrite f(x) as f(x) = frac{3}{4}cos 2x - frac{sqrt{3}}{4}sin 2x + frac{1}{2}. Now, we can express f(x) as a single cosine function with a phase shift: f(x) = frac{sqrt{3}}{2}cosleft(2x + frac{pi}{6}right) + frac{1}{2}. The maximum value of f(x) is attained when cosleft(2x + frac{pi}{6}right) = 1, which occurs when 2x + frac{pi}{6} = 2kpi for some integer k. Solving for x, we get x = kpi - frac{pi}{12}. Thus, the set of values of x for which f(x) attains its maximum value is boxed{{x mid x = kpi - frac{pi}{12}, k in mathbb{Z}}}. 2. Since A, B, and C are the internal angles of an acute triangle ABC, we have cos B = frac{3}{5}. Therefore, sin B = sqrt{1 - cos^2 B} = frac{4}{5}. Given that f(C) = -frac{1}{4}, we can write frac{sqrt{3}}{2}cosleft(2C + frac{pi}{6}right) + frac{1}{2} = -frac{1}{4}. Solving for cosleft(2C + frac{pi}{6}right), we obtain cosleft(2C + frac{pi}{6}right) = -frac{sqrt{3}}{2}. This implies 2C + frac{pi}{6} = frac{5pi}{6}, so C = frac{pi}{3}. Finally, to find sin A, we use the sine angle sum identity: sin A = sinleft(frac{2pi}{3} - Bright) = frac{sqrt{3}}{2}cos B + frac{1}{2}sin B. Substituting the values of cos B and sin B, we get sin A = frac{sqrt{3}}{2} cdot frac{3}{5} + frac{1}{2} cdot frac{4}{5} = boxed{frac{4 + 3sqrt{3}}{10}}.

question:A carpenter made 10 different styles of tables this month. For each style, he made x tables this month and x3 tables last month. Each table style has a unique size and takes a different amount of time to produce. He worked a fixed number of hours each month. The total area of tables made this month is 200 square feet and the sum of x values of all styles is 100. Find the total number of tables made in both months, considering the constraint of fixed work hours and table area.

answer:Let's denote the number of tables made this month for each style as x_1, x_2, ..., x_10, where each x_i represents the number of tables made for style i. According to the problem, the sum of all x values for this month is 100: x_1 + x_2 + ... + x_10 = 100 For last month, the number of tables made for each style would be x_1 - 3, x_2 - 3, ..., x_10 - 3. The total number of tables made last month would be: (x_1 - 3) + (x_2 - 3) + ... + (x_10 - 3) = (x_1 + x_2 + ... + x_10) - 3*10 = 100 - 30 = 70 The total number of tables made in both months would be the sum of the tables made this month and last month: Total tables = (x_1 + x_2 + ... + x_10) + ((x_1 - 3) + (x_2 - 3) + ... + (x_10 - 3)) = 100 + 70 = 170 tables However, we have the constraint that the carpenter worked a fixed number of hours each month and the total area of tables made this month is 200 square feet. This implies that the carpenter can only make a certain number of tables based on the time it takes to produce each style and the area each table occupies. Let's denote the area of each table style as A_1, A_2, ..., A_10. The total area for the tables made this month would be: A_1*x_1 + A_2*x_2 + ... + A_10*x_10 = 200 square feet Since each table style has a unique size and takes a different amount of time to produce, we cannot determine the exact number of tables made without additional information about the area and production time for each table style. However, we can say that the carpenter made boxed{170} tables in total over the two months, given the constraints of fixed work hours and the total area of tables made this month. To find the exact number of tables for each style, we would need more specific information about the area and production time for each table style.

question:For 1 le n le 150, how many integers are there such that frac{n}{n+1} is a repeating decimal?

answer:- As before, n/(n+1) is in simplest form since n and n+1 are consecutive integers, and their greatest common divisor is 1. - The fraction frac{n}{n+1} has a repeating decimal if the denominator (n+1) is not solely composed of the primes 2 and 5. - For 1 le n le 150, n+1 ranges from 2 to 151. Calculate how many of these numbers are not solely composed of the factors 2 and 5. First, list the numbers between 2 to 151 that consist only of the primes 2 and/or 5: {2, 4, 5, 8, 10, 16, 20, 25, 32, 40, 50, 64, 80, 100, 125, 128}. There are 16 such numbers. Since there are 150 values of n (from n=1 to n=150), and 16 of these result in n/(n+1) having terminating decimals, the remaining numbers will have repeating decimals. Thus, there are 150 - 16 = boxed{134} integers n such that frac{n}{n+1} is a repeating decimal.

question:Karl the old shoemaker made a pair of boots and sent his son Hans to the market to sell them for 25 talers. At the market, two people, one missing his left leg and the other missing his right leg, approached Hans and asked to buy one boot each. Hans agreed and sold each boot for 12.5 talers. When Hans came home and told his father everything, Karl decided that he should have sold the boots cheaper to the disabled men, for 10 talers each. He gave Hans 5 talers and instructed him to return 2.5 talers to each person. While Hans was looking for the individuals in the market, he saw sweets for sale, couldn't resist, and spent 3 talers on candies. He then found the men and gave them the remaining money – 1 taler each. On his way back home, Hans realized how bad his actions were. He confessed everything to his father and asked for forgiveness. The shoemaker was very angry and punished his son by locking him in a dark closet. While sitting in the closet, Hans thought deeply. Since he returned 1 taler to each man, they effectively paid 11.5 talers for each boot: 12.5 1 = 11.5. Therefore, the boots cost 23 talers: 2 cdot 11.5 = 23. And Hans had spent 3 talers on candies, resulting in a total of 26 talers: 23 + 3 = 26. But there were initially only 25 talers! Where did the extra taler come from?

answer:Let's analyze the situation in detail to understand where the calculations went wrong and what really happened with the money. 1. **Initial Plan**: Karl, the cobbler, instructed his son Hans to sell a pair of boots for 25 talers at the market. 2. **Market Situation**: At the market, Hans met two handicapped men who each needed only one boot. Hans agreed to sell one boot to each man for 12.5 talers. 3. **Total Money Collected**: Hans sold the two boots and collected a total of: [ 12.5 , text{talers} + 12.5 , text{talers} = 25 , text{talers} ] 4. **Father's Reaction**: When Hans reported this to Karl, Karl decided that each handicapped man should have paid 10 talers instead of 12.5 talers per boot. Therefore, he instructed Hans to return: [ 12.5 , text{talers} - 10 , text{talers} = 2.5 , text{talers} text{ to each man} ] 5. **Total to Return**: Karl gave Hans 5 talers to return to the two customers in total: [ 2.5 , text{talers} times 2 = 5 , text{talers} ] 6. **Discrepancy by Purchases**: While looking for the two men to return the money, Hans spent 3 talers on candy. 7. **Money Returned to Customers**: Hans found the two men and, because he had spent 3 talers, he could return only: [ 5 , text{talers} - 3 , text{talers} = 2 , text{talers} ] He gave 1 taler to each man: [ frac{2 , text{talers}}{2} = 1 , text{taler} text{ per man} ] 8. **Calculation of Effective Payments**: Each man effectively paid: [ 12.5 , text{talers} - 1 , text{taler} = 11.5 , text{talers} ] 9. **Total Money for Boots**: The total for the two boots was: [ 2 times 11.5 , text{talers} = 23 , text{talers} ] 10. **Understanding the Complete Transactions**: - Hans collected 25 talers initially by selling the boots. - Hans was given 5 talers to return. - He used 3 talers for candy. So, effectively he returned 2 talers back. 11. **Summing Collected Owing to Misinterpretation**: Hans added the 23 talers (boots) and 3 talers (candy), summing incorrectly to 26 talers instead of correctly understanding Karl received the net proceeds correctly. When looking at the final money, it actually does not create a sensible conclusion by adding spent into earnings. # Proper Financial Impact: When considering only the sale - Receipts: 23 talers (after correction of giving back 2 talers) - Expenditure: Candy (3 talers - waste ) - Karl's final correct income: originally intended 25 but effectively - 2 reps (correction returning) Therefore confirming: Hans miscalculated it including spending, instead actual clear logical difference of adjustments [ 25 presentable correct No mystery of extra taler Karl ultimately net sum - proper clarity is in recognizing not spending addition but considerate right receivable and payable track tracing correct Hassan undue lashings injustly for misinterpretation solving enigma cleaner. Conclusion: [ boxed{clear} text{ distribution Karl inline original sums outcome tracing verified }.

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