- #1
priscilla98
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Homework Statement
Prove Trig. Identities
1. sec θ (sec θ - cos θ)= tan^2 θ
Homework Equations
sec θ = 1/cos θ
tan θ = sin θ/ cos θ
cot θ = cos θ / sin θ
The Attempt at a Solution
1. sec θ * sec θ - sec θ * cos θ
1/ cos θ * 1/ cos θ - 1/ cos θ * cos θ
----> cos θ is crosses out by the right but I am confused on 1/cos θ. I know 1/cos θ = sec θ. Wait does this problem refer to the pythagorean identity which is 1 + tan^2 θ = sec^2 θ