solve the equation: 2sin^2(x)cos(x)=cos(x) on the interval 0,2pie
it is the only other question i need answers to
solve for \(\bf sin^2(x)\) what would that give you?
hint maybe
hint: linear simplification
i am going into the 12th grade and i dont get what u r saying do you think you can help me a little bit more please
think about of sin(x) = a and cos(x) = b so what you really have is -> \(\bf 2a^2b=b\)
if you were to solve for \(\bf a^2\) what would that give?
umh...0/2 maybe
hmmm \(\bf \cfrac{cos(x)}{cos(x)}=0?\)
1
am i wrong
so \(\bf 2sin^2(x)cos(x)=cos(x)\implies 2sin^2(x)=\cfrac{\cancel{ cos(x) }}{\cancel{ cos(x) }}\implies sin^2(x)=\cfrac{1}{2} \\ \quad \\ \sqrt{sin^2(x)}=\pm\sqrt{\cfrac{1}{2}}\implies sin(x)=\pm\sqrt{\cfrac{1}{2}} \\ \quad \\ \textit{taking }sin^{-1}\qquad thus \\ \quad \\ sin^{-1}[sin(x)]=sin^{-1}\left(\pm\sqrt{\cfrac{1}{2}}\right)\implies ?\)
nope.. 1 is correct... so it wouldn't be 0/2, it'd be 1/2
one thing to keep in mind I'd say. is that \(\bf sin^2(x)\to [sin(x)]^2\quad thus \quad \sqrt{sin^2(x)}\implies \sqrt{[sin(x)]^2}\to sin(x)\)
that is....
so.... \(\bf sin^{-1}[sin(x)]=sin^{-1}\left(\pm\sqrt{\cfrac{1}{2}}\right)\implies ?\)
can u maybe give me the answer
well.... skipping material is simple going to create greater issues so..... "help" here is defined as help you understand it
ok wouldnt the answer be like um a degree
yes... it does.. but you first need to solve for "x"
put it all to x or what
well..... say for example... what's the \(\bf sin(90^o)?\)
\[\sqrt{4}/2\]
hmm welll yes.. and say now what would be \(\bf sin^{-1}\left(\frac{\sqrt{4}}{2}\right)?\)
90 degrees
or pie/2
thanx i think i got it
so... you see.... then that means that \(\bf sin(90^o)={\color{brown}{ \frac{\sqrt{4}}{2}}}\qquad sin^{-1}\left({\color{brown}{ \frac{\sqrt{4}}{2}}}\right)\implies sin^{-1}\left(sin(90^o)\right)\iff 90^o\)
Join our real-time social learning platform and learn together with your friends!