Consider equation (x−sinα)(x−cosα)−2=0. Which of the following is/are true?
If 0<α<π4, then the equation has both roots in (sinα, cosα)
If π4<α<π2, then the equation has both roots in (sinα, cosα)
If 0<α<π4, then one root lies in (−∞, sinα) and the other in (cosα, ∞)
If π4<α<π2, then one root lies in (−∞, cosα) and the other in (sinα, ∞)
Let f(x)=(x−sinα)(x−cosα)−2.
Then, f(sinα)=−2<0 and f(cosα)=−2<0.
So, sinα and cosα lie between the roots.
For 0<α<π4,sinα<cosα
Therefore, equation f (x) = 0 has one root in (−∞, sinα) and other in (cosα, ∞).
Also, for π4<α<π2, cosα<sinα
Therefore, equation f(x) = 0 has one root in (−∞, cosα) and other in (sinα, ∞).