1cos(α-β) = 1
(α-β) = nπ
-2π<α-β<2π { as α,β belongs (-π,π)}
so α - β =0 → α = β .................(1)
thus cos ( α + β ) = 1e
→ cos 2α = 1e<1 which is true for values of α :
as -2π < 2α < 2π
hence answer is 4
Cos(α - β)=1 & cos(α + β)=1e ; where α,β ε [-π,π]
The number of pairs (α,β) which satisfy both the equations is --
(a) 0
(b) 1
(c) 2
(d) 4
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2 Answers
1