Kinetic Energy=(1/2)m(v^2) ;Momentum(p)=mv ;
Kinetic Energy={ (mv)^2}/2m={(p)^2}/2m
where m=Mass of a body and v=Velocity
Momentum=p
Increase in Momentum=20%
So New Momentum (p')=p * {1+ (20/100)} =1.2 p
New Kinetic energy={(p')^2}/2m
(p')^2= (1.2 p)^2=1.44 p
As mass of a body is constant
Therefore % Increase in K.E.= 44%(1.44p-p=0.44p)
Now cor 2nd question,
As 3,4 and 5 makes a Pythagorean triplet,
That means angle between 3 and 4 unit vectors is 90 degree