The number of solutions of sec2θ+cosec2θ+2cosec2θ=8 ,0≤θ≤π/2 is
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a
4
b
3
c
0
d
2
answer is D.
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Detailed Solution
We have1sin2θcos2θ+2sin2θ=8,sinθ≠0,cosθ≠0 or 1+2cos2θ=8sin2θcos2θ or 1+2cos2θ=8cos2θ1−cos2θ or 8cos4θ−6cos2θ+1=0 or 4cos2θ−12cos2θ−1=0 or cos2θ=1/4=cos2(π/3) or cos2θ=1/2=cos2(π/4) or θ=nπ±(π/3) or θ=nπ±(π/4),n∈ZHence , for 0≤θ≤π/2,θ=π/3,θ=π/4