How can this be solved?

Question

#cos^2(x) - sin^2(x) = 1 - 2sin^2(x)#

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Answer 1 · 2018-02-16T20:58:41

Add #2sin^2(x)# to both sides and the equation becomes an identity. Identities are true for all values of x.

Given: #cos^2(x) - sin^2(x) = 1 - 2sin^2(x)#

Add #2sin^2(x)# to both sides:

#cos^2(x) - sin^2(x)+ 2sin^2(x) = 1 - 2sin^2(x)+ 2sin^2(x)#

#cos^2(x) + sin^2(x) = 1 larr# this is an identity

Identities are true for all values of x.