Question

tan^2 A -1/cos^2A :A=15​

Answer 1

Answer:

Step-by-step explanation:

cot(A+15  

∘

)−tan(A−15  

∘

)=  

1+2sin2A

4cos2

​

 

L.H.S cot(A+15) - tan(A-15)

⇒  

sin(A+15)

cos(A+15)

​

−  

cos(A−15)

sin(A−15)

​

 

⇒  

sin(A+15)cos(A−15)

cos(A−15)cos(A+15)−sin(A−15)sin(A+15)

​

 

⇒  

2sin(A+15)(cos(A−15))

2cos2(A)

​

 

⇒  

sin2A+sin30

2cos2A

​

 

⇒  

[  

2

1

​

+sin2A]

2cos2A

​

 

⇒  

[1+2sin2A]

2cos2A.2

​

=  

1+2sin2A

4.cos2A

​

 R.H.S