How do you prove sec^2 theta - cos^2 theta sec^2 thetasec2θcos2θsec2θ?

1 Answer
Jun 29, 2016

See explanation to see if I answered your question. I proved that sec^2 theta - cos^2 theta sec^2 thetasec2θcos2θsec2θ equals tan^2 thetatan2θ. Please let me know if I answered your question.

Explanation:

I'm not sure what to prove here, but I think I have an idea.

sec^2 theta - cos^2 theta sec^2 thetasec2θcos2θsec2θ

sec thetasecθ always equals 1/cos theta1cosθ (Reciprocal Identity)

sec^2 theta - (cos^2 theta/1 * 1/cos^2 theta)sec2θ(cos2θ11cos2θ)

sec^2 theta - (cancel(cos^2 theta)/1 * 1/cancel(cos^2 theta))

sec^2 theta - (1)

1 + tan^2 theta always equals sec^2 theta, or 1 + tan^2 theta = sec^2 theta (Pythagorean Identity)

sec^2 theta -1

tan^2 theta