What is the derivative of f(x)=arcsin sqrt sinxf(x)=arcsinsinx?

1 Answer

One can derive the derivative for arcsinxarcsinx with implicit differentiation if it is not easy to remember it.

y = arcsinxy=arcsinx
siny = xsiny=x
cosy((dy)/(dx)) = 1cosy(dydx)=1
(dy)/(dx) = 1/(cosy) = 1/(sqrt(1-sin^2y)) = 1/(sqrt(1-x^2))dydx=1cosy=11sin2y=11x2

since sin^2x + cos^2x = 1sin2x+cos2x=1.

Thus, take this further with the Chain Rule.

d/(dx)[arcsinsqrt(sinx)] = 1/(sqrt(1-(sqrtsinx)^2)) * 1/((2sqrtsinx)) * cosxddx[arcsinsinx]=11(sinx)21(2sinx)cosx

= color(blue)(cosx/(2sqrtsinxsqrt(1-sinx)))=cosx2sinx1sinx