# constructible

1. ### 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. ### 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. ### constructible angle

is cos50 constructible? thanks in advance.
4. ### Determine if the number is constructible

Determine if the number \frac{3}{1 + \sqrt{5}} is constructible.
5. ### 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. ### 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. ### 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. ### 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. ### constructible lengths

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