Question

Which of the following is a trigonometric identity?

Options

• sin² θ = 1 + cos² θ

• cosec² θ + cot² θ = 1

• sec² θ = 1 + tan² θ

• sin 2θ = 2 sin θ

Answer 1

sec² θ = 1 + tan² θ

Explanation:

Since, sec² θ − tan² θ = 1

⇒ sec² θ = 1 + tan² θ