Q5 of 61 Page 204

If tanθ = n tanα and sinθ = m sinα, then prove that


We want to find value of cos2θ in terms of m and n.


So we first eliminate angle α,


tanθ =n tanα [∵ Given]


⇒


⇒ (1)


sinθ =m sinα [∵ Given]


⇒


⇒ (2)


We know that,


cosec2α – cot2α =1


Substituting values from (1) and (2) gives,








Hence proved.


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