Read about matlabFunction() and integral() to solve your integral numerically since the symbolic engine is not able to solve it symbollically.
syms y1
phi=(pi/180)*39;
del=(pi/180)*26;
beta=0.5;
phim=phi*beta*(1-(y1));
delm=((phim)/(phi))*del;
nup=((asin(sin(delm))/(sin(phim)))+delm)/2;
kpm=(cos(delm)/(1-sin(phim)))*(cos(delm)+sqrt((sin(phim))^2-(sin(delm))^2))*exp(2*nup*tan(phim));
fu=matlabFunction(kpm*cos(delm)*y1*y1);
Final_result=integral(fu,0.1,0.2)
command window:
Final_result =
0.0048
