If 
tan θ =1, then find the value of sin2 θ -cos2 θ.
Given: √3 tan θ = 1
⇒ tan θ = 1/√3
⇒ θ = tan-1 (1/√3) [Taking tan inverse]
⇒ θ = 30°
To find value of sin2 θ – cos2 θ, substitute value of θ
We get, sin2 30° - cos230°
= (1/2)2 – (√3/2)2
= 1/4 - 3/4
= -2/4 = -1/2
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