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Grade 10Trigonometry

If A = {x : cosx > - 1/2 and 0 ≤ x ≤ π} , B = {x : sinx > 1/2 and π/3 ≤ x ≤ π}

Then A ∩ B =

(A) [π, 5π/6)

(B) [π, 7π/6)

(C) [π/3, 2π/3)

(D) [0, 5π/6)

The given answer is:

(C) [π/3, 2π/3)

but shouldn't it be [π/6, 2π/3) ?????

Please help......

Profile image of Akshay Kandpal
14 Years agoGrade 10
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1 Answer

Profile image of Chetan Mandayam Nayakar
14 Years ago

cosx>-1/2,leads to A=[0,2π/3)

sinx>1/2 leads to B=(π/6,5π/6)

A∩B = (π/6,2π/3)

The solution in the book is wrong as you suspect.