Got Homework?
Connect with other students for help. It's a free community.
Here's the question you clicked on:
 0 viewing

This Question is Closed

beknazar23 Group TitleBest ResponseYou've already chosen the best response.0
sinx(sinx+2cosx) = 0 What can you do now? think.
 one year ago

beknazar23 Group TitleBest ResponseYou've already chosen the best response.0
if a*b = 0, Either a = 0 or b = 0 Here, a = sinx and b = sinx + 2cosx
 one year ago

satellite73 Group TitleBest ResponseYou've already chosen the best response.0
i don't think this is that easy
 one year ago

satellite73 Group TitleBest ResponseYou've already chosen the best response.0
that is \(\sin(x)=0\) is easy enough to solve, you get \(x=n\pi, n\in \mathbb{Z}\) but i can't see a good way to solve \[\sin(x)=2\cos(x)\]
 one year ago

TheViper Group TitleBest ResponseYou've already chosen the best response.0
\[sin^2x+2\ sin\ x\ cos\ x=0\] \[sin\ x(sin\ x+2\ cos\ x)=0\] \[(sin\ x+2\ cos\ x)=0\]
 one year ago

satellite73 Group TitleBest ResponseYou've already chosen the best response.0
that is not to say you cannot do it, but it is going to take some work
 one year ago

satellite73 Group TitleBest ResponseYou've already chosen the best response.0
the first thing you have to do to solve \[\sin(x)+2\cos(x)=0\] is to write it as a single function of sine
 one year ago

satellite73 Group TitleBest ResponseYou've already chosen the best response.0
in general you can write \[a\sin(x)+b\cos(x)\] as \[\sqrt{a^2+b^2}\sin(x+\theta)\]
 one year ago

tayluvsya Group TitleBest ResponseYou've already chosen the best response.0
:'( i need help on mine
 one year ago

ParthKohli Group TitleBest ResponseYou've already chosen the best response.0
I kinda wonder if you could do \(\sin^2(x) + \sin(2x)=0\).
 one year ago

satellite73 Group TitleBest ResponseYou've already chosen the best response.0
in this case you get \[\sin(x)+2\cos(x)=\sqrt{5}\sin(x+\theta)\] where \(\tan(\theta)=2\)
 one year ago

beknazar23 Group TitleBest ResponseYou've already chosen the best response.0
tanx = 2 x = atan(2) + n*(pi)
 one year ago

satellite73 Group TitleBest ResponseYou've already chosen the best response.0
therefore \(x+\theta=n\pi\) gives \(\theta=n\pi\tan^{1}(2)\)
 one year ago

satellite73 Group TitleBest ResponseYou've already chosen the best response.0
you can check that it is right by looking here http://www.wolframalpha.com/input/?i=sin%28x%29%2B2cos%28x%29
 one year ago

satellite73 Group TitleBest ResponseYou've already chosen the best response.0
@ParthKohli i don't think that identity is going to help in this case you will have two arguments, one of \(x\) and the other of \(2x\) if you have a solution from that approach i would love to see it
 one year ago

TheViper Group TitleBest ResponseYou've already chosen the best response.0
oh I had forgotten this site Thanx @satellite73 for remembering :)
 one year ago

ParthKohli Group TitleBest ResponseYou've already chosen the best response.0
Gaahh @satellite73 you were right.
 one year ago
See more questions >>>
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.