Menu Close

determinant-lim-x-0-1-x-sin-x-cos-x-sin-2-x-




Question Number 195148 by horsebrand11 last updated on 25/Jul/23
   determinant (((lim_(x→0)  ((1+x sin x−cos x)/(sin^2 x))=?)))
$$\:\:\begin{array}{|c|}{\underset{{x}\rightarrow\mathrm{0}} {\mathrm{lim}}\:\frac{\mathrm{1}+\mathrm{x}\:\mathrm{sin}\:\mathrm{x}−\mathrm{cos}\:\mathrm{x}}{\mathrm{sin}\:^{\mathrm{2}} \mathrm{x}}=?}\\\hline\end{array} \\ $$
Answered by Erico last updated on 25/Jul/23
((1+xsinx−cosx)/(sin^2 x))=((1−cosx)/(sin^2 x))+(x/(sinx))                                     = ((1−cosx)/((1−cos^2 x)))+(x/(sinx))                                     = (1/(1+cosx))+(x/(sinx))    →_(x→0)    (3/2)
$$\frac{\mathrm{1}+\mathrm{xsinx}−\mathrm{cosx}}{\mathrm{sin}^{\mathrm{2}} \mathrm{x}}=\frac{\mathrm{1}−\mathrm{cosx}}{\mathrm{sin}^{\mathrm{2}} \mathrm{x}}+\frac{\mathrm{x}}{\mathrm{sinx}} \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:=\:\frac{\mathrm{1}−\mathrm{cosx}}{\left(\mathrm{1}−\mathrm{cos}^{\mathrm{2}} \mathrm{x}\right)}+\frac{\mathrm{x}}{\mathrm{sinx}} \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:=\:\frac{\mathrm{1}}{\mathrm{1}+\mathrm{cosx}}+\frac{\mathrm{x}}{\mathrm{sinx}}\:\:\:\:\underset{\mathrm{x}\rightarrow\mathrm{0}} {\rightarrow}\:\:\:\frac{\mathrm{3}}{\mathrm{2}} \\ $$
Answered by dimentri last updated on 25/Jul/23
    ⋐
$$\:\:\:\:\underbrace{\Subset} \\ $$
Answered by SajaRashki last updated on 25/Jul/23
=^(hop) lim_(x→0) ((2sinx+xcosx)/(sin2x))  =^(hop) lim_(x→0) ((3cosx−xsinx)/(2cosx))=  =(3/2) ■
$$\overset{{hop}} {=}\underset{{x}\rightarrow\mathrm{0}} {\mathrm{lim}}\frac{\mathrm{2}{sinx}+{xcosx}}{{sin}\mathrm{2}{x}}\:\:\overset{{hop}} {=}\underset{{x}\rightarrow\mathrm{0}} {\mathrm{lim}}\frac{\mathrm{3}{cosx}−{xsinx}}{\mathrm{2}{cosx}}= \\ $$$$=\frac{\mathrm{3}}{\mathrm{2}}\:\blacksquare \\ $$

Leave a Reply

Your email address will not be published. Required fields are marked *