atanθ+bsecθ=cসমীকরণের মূলদ্বয় α,βহলে, প্রমাণ কর যে, tan(α+β)=2caa2-c2 ।
a tanθ +b secθ =c ⇒a tanθ-c =-bsecθ
a2 tan2θ + c2 -2ca tanθ = b2 + b2 tan2θ
⇒(a2-b2) tan2θ - 2ca tanθ + c2-b2=0
tanα + tanβ =2caa2-b2; tanα tanβ=c2-b2a2-b2
L.H.S= tan (α +β)=tanα + tanβ1- tanα tanβ= 2caa2-b21-c2-b2a2-b2
=2caa2-b2-c2+b2= 2caa2-c2=R.H.S (Proved)