#72 · Trigonometry · Identities

One identity, many disguises

Starting only from $sin^{2} θ + cos^{2} θ = 1$ , prove the two identities every student memorises: $1 + tan^{2} θ = sec^{2} θ$ and $1 + cot^{2} θ = csc^{2} θ$ .

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