What Trig Identities can you use to solve this problem?

tan(x)*sin(x)*cos(x)+cos(2x)

1 Answer
Jigy
May 29, 2018

tan(x)*sin(x)*cos(x)+cos(2x) = cos^2(x)

Explanation:

Identities used:

  1. tan(x)=sin(x)/cos(x)
  2. cos(2x) = cos^2(x) - sin^2(x)

tan(x)*sin(x)*cos(x)+cos(2x)
=sin(x)/cancel(cos(x))*sin(x)*cancel(cos(x))+cos(2x)
=sin^2(x)+cos(2x)
=sin^2(x)+cos^2(x) - sin^2(x)
=cancel(sin^2(x))+cos^2(x) - cancel(sin^2(x))
= cos^2(x)

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