Question # 2.12
If 1 + cosa + cosa + ........... = 2-12, then
a, (0

# 2.12
If 1 + cosa + cosa + ........... = 2-12, then
a, (0

Solution ( 1+cos x+cos ^{2} x )
( A theta )
the fate
( frac{1}{1-cos alpha} )
( frac{1}{(-cos alpha)}=alpha-52 )
( -cos alpha=frac{1}{2-sqrt{2}} times frac{2+sqrt{2}}{2+sqrt{2}} )
( x=pi-frac{pi}{4} )
( =2 )

Solution