If[{Sin[(n + 1)x] + Sinx}/x] for lim x→0 = (1/2) then value of n is: (a) - 2.5 (b) - 0.5 (c) - 1.5 (d) - 1 Weknow that cos ( A B) = cos A cos B + sin A sin B Hence A = (n + 1)x ,B = (n + 2)x Hence sin ( + 1) sin ( + 2) +cos ( + 1) cos ( + 2) = cos [ (n + 1)x (n + 2)x ] = cos [ nx + x nx 2x ] = cos [ nx nx x 2 x ] = cos (0 x ) = cos ( x) = cos x = R.H.S. Hence , L.H.S. = R.H.S. Hence proved sin(n + 1) x sin (n + 2) x + cos (n + 1) x cos (n + 2) x = cos ( ( n + 2 ) x − ( n − 1 ) x ) { ∵ cos ( A − B ) = sin A sin B + cos A cos B } ⇒ = cos ( ( n + 2 − n − 1 ) x ) a) Prove the reduction formulaintegrate cos^n(x)dx = 1/n * cos^(n-1) * x sin x + (n-1)/n * integral cos^(n-2)x dx Itis the case to consider Laurent series, since both functions have a simple pole in zero. By definition: \frac{z}{e^z-1}=\sum_{n\geq 0}\frac{B_n}{n!}z^n \tag{1} hence: \frac{1}{1-e^{-x}}=\sum_{n\geq 0}\frac{B_n}{n!}(-1)^n x^{n-1} \tag{2} Closed1 hour ago. Improve this question I am not able to do this sum the question is Prove that sin (n + 1)x sin (n + 2)x + cos (n + 1)x cos (n + 2)x = cos x So, kindly help me in doing this sum. sinn+1)-sin(n-1)x= .. Rumlah Jumlah dan Selisih Sudut; Rumus jumlah dan selisih sinus/ kosinus/ tangen; Persamaan Trigonometri; TRIGONOMETRI; Matematika Inthe particular case of your question, we have the simple algebraic identity $$(n+1)x=nx+x.$$ When applying the sine function to this quantity, we need no further parentheses on the left-hand side; but parentheses must be introduced on the right-hand side because otherwise it would read as $$\sin nx+x,$$ which is the sum of $\sin nx$ and $x$. wImUp10. If $n$ is even, then $$1= \cos^{n}x-\sin^{n}x \leq 1-0=1$$ with equality if and only if $\cos^{n}x=1, \sin^nx=0$. If $n$ is odd, $$1= \cos^{n}x-\sin^{n}x \,,$$ implies $\cosx \geq 0$ and $\sinx <0$. Let $\cosx=y, \sinx=-z$, with $y,z \geq 0$. $$y^n+z^n=1$$ $$y^2+z^2=1$$ Case 1 $n=1$ Then , since $0 \leq y,z \leq 1$ we have $$1 =y+z \geq y^2+z^2 =1$$ with equality if and only if $y=y^2, z=z^2$. Case 2 $n \geq 3$ Then , since $0 \leq y,z \leq 1$ we have $$1 =y^2+z^2 \geq y^n+z^n =1$$ with equality if and only if $y^2=y^n, z^2=z^n$. I have researched the question $\lim_{n \to \infty} n*\sin\frac{1}{n}$ quite profusely, and I know that it equals to 1, and I know why A You can use a change of variables and substitute, say, $m = \frac{1}{n}$ so that $m \to 0$ instead. B L'Hopital's rule The problem is, we haven't used either of these methods in class, so I am wondering if there is any other possible way to approach this question? Calculus Examples Popular Problems Calculus Solve for x k=1+sinx/n Step 1Rewrite the equation as .Step 2Multiply both sides by .Step 3Simplify the left for more steps...Step .Tap for more steps...Step the common factor of .Tap for more steps...Step the common the and .Step 4Subtract from both sides of the 5Take the inverse sine of both sides of the equation to extract from inside the sine.