The expression tanA1-cotA+cotA1-tanA can be written as: [2013]
sinAcosA+1
secAcosecA+1
tanA+cotA
secA+cosecA
(2)
Given expression can be written as
sinAcosA×sinAsinA-cosA+cosAsinA×cosAcosA-sinA
=1sinA-cosA{sin3A-cos3AcosAsinA}
∵ a3-b3=(a-b)(a2+ab+b2)
=sin2A+sinAcosA+cos2AsinAcosA=1+secAcosecA
Given both θ and ϕ are acute angles and sinθ=12,cosϕ=13, then the value of θ+ϕ belongs to [2004]
(π3,π2]
(π2,2π3)
(2π3,5π6]
(5π6,π]
Given: sinθ=12 and θ is acute angle
∴ θ=π6
Also given, cosϕ=13 and ϕ is acute angle.
∴ 0<13<12
⇒cosπ2<cosϕ<cosπ3 or π3<ϕ<π2
∴ π3+π6<θ+ϕ<π2+π6 or π2<θ+ϕ<2π3
⇒θ+ϕ∈(π2,2π3)