1. O

    Set Theory - Godel's Constructible Universe (Kunen)

    Hi, I have a question about Godel's Constructible Universe. I think the best way to ask the question is to refer directly to the book that I'm using: Set Theory, Introduction To Independence Proofs by Kenneth Kunen. My question is about the proof of 1.9 Lemma on p167. In the second paragraph...
  2. E

    constructible angle

    cosθ=3/7, θ is an acute angle. prove θ cannot be trisected with straightedge and compass? my approach: angle θ can't be constructed with straightedge and compass if cosθ is transcendental, but cosθ=3/7 is algebraic and so it is not transcendental? Please help me with this question...
  3. E

    constructible angle

    is cos50 constructible? thanks in advance.
  4. F

    Determine if the number is constructible

    Determine if the number \frac{3}{1 + \sqrt[8]{5}} is constructible.
  5. J

    constructible or not?

    If the angle x is constructible, is the number tan(x) and sec(x) constructible? hat about the converse? since angle x isconstructible, sin(x) and cos(x) is constructible. how do I start from where?
  6. J

    prove a function has no constructible roots

    prove that x^6 - x^2 + 2 has no constructible roots First, i let y=x^2, so the function become y^3 - y + 2 then use the theorem, if polynomial f(x) has integer coefficient and a ration root p/q. (p,q)=1, then p|a0 , q|an. I got p|2 and q|1 g(2) does not equal to zero. so. the...
  7. D

    constructible number

    a = 3^(1/5) can anyone give me a reason why a is or isnt a constructible number thanks(topic galois theory)
  8. A

    constructible angle

    The measure of a given angle is 180o n , where n is a positive integer not divisible by 3. Prove that this angle can be trisected by Eucliden means (straightedge and compass).
  9. P

    constructible lengths

    Prove that if a real number, a, is constructible, then the real number (a/3) is also constructible.