Got Homework?
Connect with other students for help. It's a free community.
Here's the question you clicked on:
 0 viewing
aussy123
Group Title
Given: costheta= 4/5, sin x =12/13 ,theta is in the third quadrant, and x is in the fourth quadrant; evaluate cos 2x.
119/169
119/169
11/13
 one year ago
 one year ago
aussy123 Group Title
Given: costheta= 4/5, sin x =12/13 ,theta is in the third quadrant, and x is in the fourth quadrant; evaluate cos 2x. 119/169 119/169 11/13
 one year ago
 one year ago

This Question is Closed

satellite73 Group TitleBest ResponseYou've already chosen the best response.1
you don't need the sine part
 one year ago

aussy123 Group TitleBest ResponseYou've already chosen the best response.0
then how do I start
 one year ago

terenzreignz Group TitleBest ResponseYou've already chosen the best response.0
Two variables?
 one year ago

satellite73 Group TitleBest ResponseYou've already chosen the best response.1
\[\cos(2x)=2\cos^2(x)1\]
 one year ago

tomhoffhim Group TitleBest ResponseYou've already chosen the best response.0
dw:1364529999084:dw
 one year ago

satellite73 Group TitleBest ResponseYou've already chosen the best response.1
oh i see there is a \(\theta\) and an \(x\)
 one year ago

aussy123 Group TitleBest ResponseYou've already chosen the best response.0
costheta= 4/5 I need cosx
 one year ago

satellite73 Group TitleBest ResponseYou've already chosen the best response.1
you are asked for \(\cos(2x)\) where \(\sin(x)=\frac{12}{13}\)
 one year ago

satellite73 Group TitleBest ResponseYou've already chosen the best response.1
\[\cos(2x)=12\sin^2(x)\]
 one year ago

aussy123 Group TitleBest ResponseYou've already chosen the best response.0
When I do it I get 169
 one year ago

aussy123 Group TitleBest ResponseYou've already chosen the best response.0
a denominator of 169
 one year ago

satellite73 Group TitleBest ResponseYou've already chosen the best response.1
there is no \(\theta \) in your question
 one year ago

tomhoffhim Group TitleBest ResponseYou've already chosen the best response.0
ok, I'll do it for you, give me a second, this is an easy question
 one year ago

aussy123 Group TitleBest ResponseYou've already chosen the best response.0
yea I had to put theta for that
 one year ago

tomhoffhim Group TitleBest ResponseYou've already chosen the best response.0
satellite, you don't know what you're doing..
 one year ago

satellite73 Group TitleBest ResponseYou've already chosen the best response.1
\[\cos(x)=12\sin^2(x)\] \[\cos(x)=1(\frac{12}{13})^2\]\
 one year ago

satellite73 Group TitleBest ResponseYou've already chosen the best response.1
there is your 169
 one year ago

satellite73 Group TitleBest ResponseYou've already chosen the best response.1
\[\cos(2x)=1(\frac{12}{13})^2\] \[\cos(2x)=1\frac{144}{169}\]
 one year ago

satellite73 Group TitleBest ResponseYou've already chosen the best response.1
\[\cos(2x)=\frac{25}{169}\]
 one year ago

aussy123 Group TitleBest ResponseYou've already chosen the best response.0
I know, thats what I get, but it isnt a choice
 one year ago

satellite73 Group TitleBest ResponseYou've already chosen the best response.1
your question asks for \(\cos(2x)\) and doesn't mention any \(\theta\)
 one year ago

aussy123 Group TitleBest ResponseYou've already chosen the best response.0
I know but that is what is already given
 one year ago

satellite73 Group TitleBest ResponseYou've already chosen the best response.1
oh damn i made a mistake!! sorry
 one year ago

tomhoffhim Group TitleBest ResponseYou've already chosen the best response.0
I'm too lazy to do it but you need to draw the triangles and either use theta or x for the angle
 one year ago

aussy123 Group TitleBest ResponseYou've already chosen the best response.0
lol its okay, Ive made plenty
 one year ago

satellite73 Group TitleBest ResponseYou've already chosen the best response.1
\[\cos(2x)=12\sin^2(x)\] \[\cos(2x)=12\times (\frac{12}{13})^2\] \[cos(2x)=12\times \frac{144}{169}\]
 one year ago

satellite73 Group TitleBest ResponseYou've already chosen the best response.1
\[\cos(2x)=1\frac{288}{169}\]\[\cos(2x)=\frac{119}{169}\]
 one year ago

aussy123 Group TitleBest ResponseYou've already chosen the best response.0
Lol this is a lot of work, can you use this same formula for tan2Theta
 one year ago

aussy123 Group TitleBest ResponseYou've already chosen the best response.0
nvm. I found the formula, Thank you!
 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.