NIMCET 2019 — Mathematics PYQ
NIMCET | Mathematics | 2019If sin2xtanx+cos2cotx−sin2x=1+tanx+cotx, x∈(0,π), then
Choose the correct answer:
- A.
123π,125π,127π
127π,1211π,129π
Explanation
Concept:
- tanθ=cosθsinθ
- sin2x+cos2x=1
- sin4x+cos4x=1−2sin2xcos2x
Calculation:
Given: sin2xtanx+cos2cotx−sin2x=1+tanx+cotx
⇒cosxsin2x+sinxcos3x−sin2x=1+cosxsinx+sinxcosx
⇒sinxcosxsin2x+cos4x−sin2x=1+sinxcosxsin2x+cos2x
⇒sinxcosx1−2sin2xcos2x−sin2x=1+sinxcosx1
⇒sinxcosx1−sinxcosx2sin2xcos2x−sin2x=1+sinxcosx1
⇒−2sinxcosx−sin2x=1
⇒−2sin2x=1
⇒sin2x=−21
⇒2x=67π,611π
⇒x=127π,1211π
Explanation
Concept:
- tanθ=cosθsinθ
- sin2x+cos2x=1
- sin4x+cos4x=1−2sin2xcos2x
Calculation:
Given: sin2xtanx+cos2cotx−sin2x=1+tanx+cotx
⇒cosxsin2x+sinxcos3x−sin2x=1+cosxsinx+sinxcosx
⇒sinxcosxsin2x+cos4x−sin2x=1+sinxcosxsin2x+cos2x
⇒sinxcosx1−2sin2xcos2x−sin2x=1+sinxcosx1
⇒sinxcosx1−sinxcosx2sin2xcos2x−sin2x=1+sinxcosx1
⇒−2sinxcosx−sin2x=1
⇒−2sin2x=1
⇒sin2x=−21
⇒2x=67π,611π
⇒x=127π,1211π

