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Trigonometry 20 Online
OpenStudy (dawnr):

what is the largest value of the function f(x)=sin(sinx)?

OpenStudy (rational):

got options ?

OpenStudy (dawnr):

so this is what i did: y=sin(sinx) sinx=u(x) u'(x)=cosx y'=(sin(u))'*u'(x) = sinx*cosx and sinx*cosx=sin2x/2 so i got that y'=sin2x/2 and this is where i'm stuck

OpenStudy (dawnr):

the correct answer should be sin1

OpenStudy (ikram002p):

0 \(\le\) sin x\(\le\) 1 :D take sin x for all sin (0) \(\le\) sin (sin x)\(\le\) sin (1)

OpenStudy (rational):

so this is what i did: y=sin(sinx) sinx=u(x) u'(x)=cosx y'=(sin(u))'*u'(x) = sinx*cosx *************** and sinx*cosx=sin2x/2 so i got that y'=sin2x/2 and this is where i'm stuck

OpenStudy (rational):

that like has a mistake

OpenStudy (rational):

you should get : y' = cos(sinx) * cosx

OpenStudy (rational):

set it equal to 0 and find your critical points

OpenStudy (dawnr):

so cos(sinx)*cosx=0 and is there a way to simplify this or?! :/

OpenStudy (rational):

use zero product property : ab = 0 means 1) a = 0 or 2) b = 0 or 3) a, b = 0

OpenStudy (rational):

cos(sinx)*cosx=0 means cos(sinx) = 0 OR cosx = 0

OpenStudy (dawnr):

rightt so dor cos(sinx)=0 sinx=1

OpenStudy (dawnr):

for*

OpenStudy (dawnr):

i'm so slow today xD

OpenStudy (rational):

nope, try again

OpenStudy (rational):

\(\cos(\sin x) = 0\) \(\sin x = \arccos (0) = \dfrac{\pi}{2}\) \(x = \arcsin (\frac{\pi}{2}) = 1\)

OpenStudy (rational):

solve the other case also : cosx = 0

OpenStudy (ikram002p):

@rational is the domain /range method work ?

OpenStudy (ikram002p):

does*

OpenStudy (rational):

it works right ?

OpenStudy (rational):

but he is trying to solve it using calculus... so im just trying to help him solve it in his own way..

OpenStudy (ikram002p):

ic..

OpenStudy (rational):

solving cosx = 0 gives x = pi/2 so the critical points are : \(\large x = 1, \pi /2 \)

OpenStudy (rational):

evaluate f(x) at these points and the maximum value u get is the maximum value of f(x)

OpenStudy (rational):

f(x) = sin(sinx) f(1) = ? f(pi/2) = ?

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