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42

Step-by-step explanation:

cos 100⁰ =( 25² + 30²-x²)/2×25×30

1500×cos100⁰-25²-30²= -x²

x² = -1500× cos 100⁰ +25²+30²

x² = -1500 × - 0.173 +625+900

x²= 259.5 +625+900

x²=1784.5

x=42.24

nearest to 10: 42

reduce the friction between its moving parts

step-by-step explanation:

in fact, by reducing the friction between the moving parts of the machine, it is possible to reduce the energy wasted due to this friction; therefore, more input energy is converted into useful work, and this will improve the efficiency of the machine.

step-by-step explanation:

descending order means to order the polynomials from the term with the largest exponent to the term with the smallest exponent.  

therefore, the correct answer is d.