E=cot−1(cot(−11))+10sin(2cos−121)+10sin(2tan−12)
To find E using principal values
choose the correct option
1. cot−1(cot(−11)) to its principal value
2. 10sin(2cos−121)
3. 10sin(2tan−12)
cot−1:range (0,π)
cot(θ+π)=cotθ⇒cot(−11)=cot(−11+kπ)
−11+4π≈1.566∈(0,π)✓
cot−1(cot(−11))=4π−11
cos−121=4π ⇒ 2cos−121=2π
10sin2π=10⋅1=10
θ=tan−12⇒tanθ=2
sin2θ=1+tan2θ2tanθ
sin2θ=1+222⋅2=54
10sin(2tan−12)=10⋅54=8
E=(4π−11)+10+8=4π+7
E=4π+7 ⇒ option (3)