Question

trigononmetry (factorise )
a) cos2 A +sin2A×cos2A
B) tan3 A - cot 3 A
c) sec4A- cosec4 A​

Answer 1

Step-by-step explanation:

a) Let us start with LHS

cos 2A can be expressed as

cos 2A= cos (A + A)

Using the identity

cos(A+B)=cos(A)⋅cos(B)−sin(A)⋅sin(B)

cos 2A= cos A.cos A-sin A.sinA

= cos2A – sin2A

= RHS

Hence Proved

b)

Answer 2

Answer:

Step-by-step explanation:

a) Let us start with LHS

cos 2A can be expressed as

cos 2A= cos (A + A)

Using the identity

cos(A+B)=cos(A)⋅cos(B)−sin(A)⋅sin(B)

cos 2A= cos A.cos A-sin A.sinA

= cos2A – sin2A

= RHS

Hence Proved

b)