Is LHS=RHS ? secθ+1−tanθsecθ+1+tanθ+tanθ+secθ−1tanθ−secθ+1=2secθ
Say true or false.
A
True
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B
False
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C
Ambiguous
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D
Data insufficient
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Solution
The correct option is A True =tanA+secA−1tanA−secA+1 =sinA+1−cosAsinA−1+cosA =sinA+(1−cosA)sin−(1−cosA) =(sinA+1−cosA)2sin2A−(1−cosA)2 =sin2A+cos2+1−2sinAcosA−2cosA+2sinA(1−cos2A)−(1−cosA)2 =2−2sinAcosA−2cosA+2sinA(1−cosA)(1+cosA−1+cosA) =2(1−cosA)+2sinA(1−cosA)(1−cosA)(2cosA) =secA+tanA ......(i) And
secA+1−tanAsecA+1+tanA =1+cosA−sinA1+cosA+sinA =(1+cosA−sinA)2(1+cosA)2−sin2A =1+cos2A+sin2A−2cosAsinA−2sinA+2cosA(1+cosA)2−(1−cosA)(1+cosA) =2−2cosAsinA−2sinA+2cosA(1+cosA)(1+cosA−1+cosA) =2(1+cosAsinA−sinA+cosA)2cosA(1+cosA) =1+cosAsinA−sinA+cosAcosA(1+cosA) =(1+cosA)−sinA(1+cosA)cosA(1+cosA) =secA−tanA ...(ii) Adding (i)and(ii), we get 2secA