If 5 +12 cot θ = cosec θ and 12 - 5cot θ = Kcosec θ, then find K² ?
Answer & explanation
Correct answer: option 3
5 + 12cot θ = cosec θ 12 - 5 cot θ = Kcosec θ
square both side
52 + 144cot2 θ + 120cot θ= cosec2 θ ....(i)
144 + 25cot2 θ - 120cot θ = K2cosec2 θ .... (ii)
add (i) and (ii)
(52 + 122) + (122 + 52 ) cot2 θ = cosec2 θ (1+ K2)
132 + 132cot2 θ = cosec2 θ (1+ K2)
132 (1+ cot2 θ) = cosec2 θ (1+ K2)
169 cosec2 θ = cosec2 θ (1+ K2)
K2 = 168