A community for students.
Here's the question you clicked on:
 0 viewing
anonymous
 4 years ago
cos67degrees 30'= ?
anonymous
 4 years ago
cos67degrees 30'= ?

This Question is Closed

ash2326
 4 years ago
Best ResponseYou've already chosen the best response.1@IloveCharlie what's 30' in degrees?

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0Divide 30 seconds by 60. After that, add it to 67. Then take the cosine of it all.

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0Hmmm... I got .382. Can you please confirm?

ash2326
 4 years ago
Best ResponseYou've already chosen the best response.1yeah, it's right but could you use calculator for this? @IloveCharlie

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0I just don't know which one it matches up with :/ From the options given

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0Whoa @jim_thompson5910 you're typing a lot

jim_thompson5910
 4 years ago
Best ResponseYou've already chosen the best response.1Yes it's a lot, but it at least gives you the exact answer 67 degrees 30' = 67 degrees + 30/60 = 67+0.5 = 67.5 degress Notice how 2*67.5 = 135 and \[\Large \cos(135) = \frac{\sqrt{2}}{2}\] (using the unit circle) Now turn to the identity \[\Large \cos(x) = \sqrt{ \frac{ \cos(2x) + 1 }{2} }\] If we let x = 67.5, then \[\Large \cos(x) = \sqrt{ \frac{ \cos(2x) + 1 }{2} }\] \[\Large \cos(67.5) = \sqrt{ \frac{ \cos(2*67.5) + 1 }{2} }\] \[\Large \cos(67.5) = \sqrt{ \frac{ \cos(135) + 1 }{2} }\] \[\Large \cos(67.5) = \sqrt{ \frac{ \frac{\sqrt{2}}{2} + 1 }{2} }\] \[\Large \cos(67.5) = \sqrt{ \frac{ \frac{\sqrt{2}}{2} + \frac{2}{2} }{2} }\] \[\Large \cos(67.5) = \sqrt{ \frac{ \frac{\sqrt{2}+2}{2} }{2} }\] \[\Large \cos(67.5) = \sqrt{ \frac{ \frac{2\sqrt{2}}{2} }{2} }\] \[\Large \cos(67.5) = \sqrt{ \left( \frac{2\sqrt{2}}{2} \right)\left(\frac{1}{2}\right) }\] \[\Large \cos(67.5) = \sqrt{ \frac{(2\sqrt{2})*1}{2*2} }\] \[\Large \cos(67.5) = \sqrt{ \frac{2\sqrt{2}}{4} }\] \[\Large \cos(67.5) = \frac{\sqrt{2\sqrt{2}}}{\sqrt{4}}\] \[\Large \cos(67.5) = \frac{\sqrt{2\sqrt{2}}}{2}\]

jim_thompson5910
 4 years ago
Best ResponseYou've already chosen the best response.1sry i had a typo, but i fixed it

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0Wow, thanks so much for the awesome step by step explanation! Really helps!

jim_thompson5910
 4 years ago
Best ResponseYou've already chosen the best response.1you're welcome
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.