‌tan(π‌cos‌θ)+tan(πsin‌θ)=0 ‌tan(π‌cos‌θ)=−tan(πsin‌θ) ‌tan(π‌cos‌θ)=tan(−πsin‌θ) ‌π‌cos‌θ=nπ−πsin‌θ ‌sin‌θ+cos‌θ=n‌ where ‌n∈I possible values are n=0,1 and −1 because −√2≤sin‌θ+cos‌θ≤√2 Now it gives θ∈{0,‌