Question

1
(vi) cosec
4 cos3 2x – 3 cos 2x​

Answer 1

Answer:

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Answer 2

cos2x−3cosx=4cos  

2

x/2

⇒cos2x−3cosx=2(1+cosx)

⇒cos2x−3cosx=2+2cosx

⇒2cos  

2

x−1−3cosx−2−2cosx=0

⇒2cos  

2

x−5cosx−3=0

⇒2cos  

2

x−cosx+cosx−3=0

⇒2cosx(cosx−3)+(cosx−3)=0

cosx=−1/2 or cosx=3

⇒x=2mπ±2π/3 cos2x−3cosx=4cos  

2

x/2

⇒cos2x−3cosx=2(1+cosx)

⇒cos2x−3cosx=2+2cosx

⇒2cos  

2

x−1−3cosx−2−2cosx=0

⇒2cos  

2

x−5cosx−3=0

⇒2cos  

2

x−cosx+cosx−3=0

⇒2cosx(cosx−3)+(cosx−3)=0

cosx=−1/2 or cosx=3

⇒x=2mπ±2π/3 cos2x−3cosx=4cos  

2

x/2

⇒cos2x−3cosx=2(1+cosx)

⇒cos2x−3cosx=2+2cosx

⇒2cos  

2

x−1−3cosx−2−2cosx=0

⇒2cos  

2

x−5cosx−3=0

⇒2cos  

2

x−cosx+cosx−3=0

⇒2cosx(cosx−3)+(cosx−3)=0

cosx=−1/2 or cosx=3

⇒x=2mπ±2π/3 cos2x−3cosx=4cos  

2

x/2

⇒cos2x−3cosx=2(1+cosx)

⇒cos2x−3cosx=2+2cosx

⇒2cos  

2

x−1−3cosx−2−2cosx=0

⇒2cos  

2

x−5cosx−3=0

⇒2cos  

2

x−cosx+cosx−3=0

⇒2cosx(cosx−3)+(cosx−3)=0

cosx=−1/2 or cosx=3

⇒x=2mπ±2π/3