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NWeid1
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I'm so bad with the Mean Value Theorem. Can someone help me prove that, if f(x)=sinx, that, for any given a and b, |sinb-sina|<=|b-a|. Explain if you could too, please. Thanks a lot.
gb7nash said:x = y → |x| = |y|
NWeid1 said:|sin(b)-sin(a)| = |f'(c)(b-a)|
NWeid1 said:f'(x) = cosx so f'(c) = cos(c).
NWeid1 said:|sin(b)-sin(a)| = |cos(c)||b-a|. And -1<=cosx<=1 so would it be |sin(b)-sin(a)| <= 1|b-a| ?
MVT (Mean Value Theorem) is a fundamental theorem in calculus that states that if a function is continuous on a closed interval [a,b] and differentiable on the open interval (a,b), then there exists at least one point c in (a,b) where the slope of the tangent line at c is equal to the average slope of the function over [a,b]. This theorem is important in proving many other theorems and in solving optimization problems.
The function f(x)=sinx is a trigonometric function that represents the ratio of the side opposite to an angle in a right triangle to the hypotenuse. It is commonly used in mathematical and scientific applications to model periodic phenomena such as sound waves and oscillations.
To show that |sina-sinb|<=|b-a|, we can use the MVT (Mean Value Theorem). Let f(x)=sinx, a and b be two points in [a,b]. By the MVT, there exists a point c in (a,b) such that f'(c)=(f(b)-f(a))/(b-a). Since f'(x)=cosx, we have cosc=(sinb-sina)/(b-a). Then, taking the absolute value on both sides, we get |cosc|=|(sinb-sina)/(b-a)|=|sina-sinb|/|b-a|. Since the cosine function is bounded between -1 and 1, we have |cosc|<=1, which implies |sina-sinb|<=|b-a|.
This inequality represents the fact that the difference between the values of the sine function at two points a and b is always less than or equal to the distance between a and b. Geometrically, this means that the slope of the line connecting two points on the graph of the sine function is always less than or equal to the slope of the secant line connecting these two points.
The Mean Value Theorem has many real-life applications. For example, it is used in physics to calculate the average velocity of an object in motion, in economics to determine the average rate of change of a variable, and in engineering to analyze the stability of a system. It is also used in optimization problems to find the maximum or minimum value of a function. The MVT is a powerful tool that helps us understand the behavior of functions and solve various real-life problems.