A community for students.
Here's the question you clicked on:
 0 viewing
Henry.Lister
 3 years ago
Show that Cos(22.5) = 1/2.root(2+root(2))
Henry.Lister
 3 years ago
Show that Cos(22.5) = 1/2.root(2+root(2))

This Question is Closed

Henry.Lister
 3 years ago
Best ResponseYou've already chosen the best response.0\[\cos 22.5 = \frac{ 1 }{ 2 }\sqrt{2+\sqrt{2}}\]

mukushla
 3 years ago
Best ResponseYou've already chosen the best response.122.5=45/2 ... so i'd probably say use half angle formula for cos :\[\cos^2\theta=\frac{1+\cos 2 \theta }{2}\]

Henry.Lister
 3 years ago
Best ResponseYou've already chosen the best response.0Walk me through the steps?

Zekarias
 3 years ago
Best ResponseYou've already chosen the best response.1\[\cos(45)=\cos(22.5+22.5)=\cos^{2}(22.5)\sin^{2}(22.5)......but...\sin^{2}(22.5)=1\cos^{2}(22.5)\]\[\cos(45)=2\cos^{2}(22.5)1\]\[\frac{ \cos(45)+1 }{ 2 }=\cos^{2}(22.5)\]\[\cos(22.5)=\sqrt{\frac{ \cos(45) +1}{ 2}}\]then you do it
Ask your own question
Sign UpFind more explanations on OpenStudy
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.