Open study

is now brainly

With Brainly you can:

  • Get homework help from millions of students and moderators
  • Learn how to solve problems with step-by-step explanations
  • Share your knowledge and earn points by helping other students
  • Learn anywhere, anytime with the Brainly app!

A community for students.

Help... Prove that sin36 degrees = sqrt[10 - 2*sqrt(5)]/4

I got my questions answered at in under 10 minutes. Go to now for free help!
At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat.

Join Brainly to access

this expert answer


To see the expert answer you'll need to create a free account at Brainly

HINT: 180º/5 = 36º
next, what's formula using i do
Seems like it won't help. Try this, using the formula sin (a + b) = cosa sinb + cosb sin a sin36º = 2 sin18º cos18º = 2 cos72º sin72º

Not the answer you are looking for?

Search for more explanations.

Ask your own question

Other answers:

ok, i know that formula.. but i think we get the new problem... because sin/cos 18 or sin/cos 72 not eassy to get.. it's very difficul, right ?
It seems so. Bump your question to get more helps. Maybe someone can help you with this.
ok, thanks...
@cwrw238 , @experimentX , @estudier , @Hero , @Zarkon , @sauravshakya , @all... help me please, how to get it
any idea guys ?
|dw:1350231015827:dw||dw:1350231152168:dw| Use quadratic formula |dw:1350231253477:dw| |dw:1350231349862:dw|
@ajprincess try this|dw:1350231460480:dw|
ok, i get |dw:1350231717622:dw|
next ?
upss. sorry, divided 8
@experimentX I tried bt it is a bit complex. cos sin3x=sin108.
Getting it @tanjung?
this should be simpler ... sin(3x) = sin(2x)
not yet, what should i do after that
since this is just double angle and triple angle ... change everything back to sin ... and remove all roots and try to factorize it.
so, just take positive sign in sqrt ?
i know that +- it means there are two number here. what about u for it
with positive sign u have sin 36>1 thats impossible
oh yea, i understand now... thank u very much for ur help , @ajprincess and @mukushla

Not the answer you are looking for?

Search for more explanations.

Ask your own question