Ask your own question, for FREE!
Mathematics 7 Online
OpenStudy (anonymous):

find all solutions of the given equation in the interval [0,2pi] cosx=cos3x

OpenStudy (anonymous):

\[\pi\] would work

OpenStudy (anonymous):

i guess 0 would work as well. and maybe \[\frac{\pi}{2}\]

OpenStudy (anonymous):

maybe write 4cos^3(x) - 3cos(x) = cos(3x) (as this is an identity i think (correct me if i am wrong) Then obviously: cos(x) = 4cos^3(x) - 3cos(x) hence 0 = 4cos(x)(cos^2(x) - 1) so you can tell right away that all the places where cos(x) vanishes in that interval are solutions. Next solve cos^2(x) -1 = 0 for x to find the others

OpenStudy (anonymous):

@Callum, yes, that is the correct identity. This is how I would do the problem.

Can't find your answer? Make a FREE account and ask your own questions, OR help others and earn volunteer hours!

Join our real-time social learning platform and learn together with your friends!
Latest Questions
XShawtyX: Art, Short Writing Assignment: Imagining Landscapes
5 hours ago 2 Replies 0 Medals
XShawtyX: Chemistry, Help ud83dude4fud83cudffe
5 hours ago 13 Replies 1 Medal
kaelynw: tried a lil smt, the arm is off but i like the other stuff
16 hours ago 27 Replies 3 Medals
kaelynw: art igg
14 hours ago 14 Replies 2 Medals
XShawtyX: Art
3 days ago 6 Replies 0 Medals
Nina001: teach me how to draw or just tell me the basics
3 days ago 2 Replies 1 Medal
XShawtyX: We doing another drawing gimme ideas to add to this
3 days ago 9 Replies 1 Medal
Can't find your answer? Make a FREE account and ask your own questions, OR help others and earn volunteer hours!

Join our real-time social learning platform and learn together with your friends!