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Find 
lim_(x rarr(pi)/(2))(sin(2x))/(cos(x)).
Choose 1 answer:
(A) 
(1)/(2)
(B) 1
(C) 2
(D) The limit doesn't exist

Find limxπ2sin(2x)cos(x) \lim _{x \rightarrow \frac{\pi}{2}} \frac{\sin (2 x)}{\cos (x)} .\newlineChoose 11 answer:\newline(A) 12 \frac{1}{2} \newline(B) 11\newline(C) 22\newline(D) The limit doesn't exist

Full solution

Q. Find limxπ2sin(2x)cos(x) \lim _{x \rightarrow \frac{\pi}{2}} \frac{\sin (2 x)}{\cos (x)} .\newlineChoose 11 answer:\newline(A) 12 \frac{1}{2} \newline(B) 11\newline(C) 22\newline(D) The limit doesn't exist
  1. Identify Limit: Identify the limit that needs to be evaluated.\newlineWe need to find the limit of the function sin(2x)cos(x)\frac{\sin(2x)}{\cos(x)} as xx approaches π2\frac{\pi}{2}.
  2. Direct Substitution: Direct substitution to check if the limit can be evaluated directly.\newlineIf we substitute x=π2x = \frac{\pi}{2} directly into the function, we get sin(π)/cos(π2)\sin(\pi)/\cos(\frac{\pi}{2}). Since sin(π)=0\sin(\pi) = 0 and cos(π2)=0\cos(\frac{\pi}{2}) = 0, we have an indeterminate form of 0/00/0. This means we cannot find the limit by direct substitution.
  3. Apply L'Hôpital's Rule: Apply L'Hôpital's Rule to evaluate the limit. L'Hôpital's Rule states that if the limit of functions f(x)f(x) and g(x)g(x) as xx approaches a value cc is an indeterminate form 0/00/0 or /\infty/\infty, then the limit of f(x)/g(x)f(x)/g(x) as xx approaches cc is the same as the limit of their derivatives f(x)/g(x)f'(x)/g'(x), provided this limit exists.
  4. Differentiate Functions: Differentiate the numerator and denominator.\newlineThe derivative of sin(2x)\sin(2x) with respect to xx is 2cos(2x)2\cos(2x), and the derivative of cos(x)\cos(x) with respect to xx is sin(x)-\sin(x).
  5. Apply Derivatives: Apply L'Hôpital's Rule using the derivatives.\newlineNow we need to find the limit of (2cos(2x))/(sin(x))(2\cos(2x))/(-\sin(x)) as xx approaches π/2\pi/2.
  6. Substitute Values: Substitute x=π2x = \frac{\pi}{2} into the derivatives.\newlineSubstituting x=π2x = \frac{\pi}{2} into the derivatives, we get 2cos(π)sin(π2)\frac{2\cos(\pi)}{-\sin(\frac{\pi}{2})}. Since cos(π)=1\cos(\pi) = -1 and sin(π2)=1\sin(\frac{\pi}{2}) = 1, the expression simplifies to 2×11\frac{2 \times -1}{-1} which equals 22.
  7. Conclude Limit: Conclude the limit.\newlineThe limit of sin(2x)cos(x)\frac{\sin(2x)}{\cos(x)} as xx approaches π2\frac{\pi}{2} is 22.

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