Prove that (sin θ + cosec θ)2 + (cos θ + sec θ)2 = 7 + tan2 θ + cot2θ.
Given L.H.S. = (sin θ + cosec θ)2 + (cos θ + sec θ)2
We know
⇒ sin2 θ + cosec2 θ + 2 + cos2 θ + sec2 θ + 2
Also From the Trigonometrical identities
sin2θ + cos2θ = 1
cosec2 θ = 1 + cot2 θ
sec2 θ = 1 + tan2 θ
⇒ 1 + 1 + cot2 θ + 2 + 1 + tan2 θ + 2
⇒ 7 + cot2 θ + tan2 θ
So, L.H.S = R.H.S
Hence Proved