5.
12, 12 angle of 20.
To find the other one, law of cosines.
x^2 = 12^2+12^2 - 2*12*12*cos(20 degrees)
x^2 = 17.3685252137
x = 4.16755626401
Oh no, it looks like we got different answers. :((
=^._.^=
5) R = 12 ∠θ = 120º (NOT 20 )
Chord C = 2[ sqrt(122 - 62)]
But..., if ∠θ = 20º then the answer is "slightly" different:
C = 2[sin(10º) * 12] ==> 24 sin(10º)