Question 889599
Sin(x).tan(x)/cos(x) + 1 = 1/cos^2(x)

Prove the identity
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Sin(x)*tan(x)/cos(x) + 1 = 1/cos^2(x)
Sin^2(x)/cos^2(x) + 1 = 1/cos^2(x)
tan^2 + 1 = sec^2
QED