# Prove that :sin2 25o+sin2 65° = cos2 63°+cos2 39o

Taking LHS = sin 25o+sin65o

We know that

Sin θ = cos (90° - θ)

Here, θ = 25°

cos2 (90° - 25°)+ sin2 65°

cos2 65° + sin2 65°

= 1 [ cos2 θ + sin2 θ = 1]

Now, RHS = cos2 63o+cos2 39o

We know that

cos θ = sin (90° - θ)

Here, θ = 39°

cos2 63° + sin2 (90° - 39°)

cos2 63°+ sin2 63°

=1 [ cos2 θ + sin2 θ = 1]

LHS = RHS

Hence Proved

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