If x = a sec θ + b tan θ and y = a tan θ + b sec θ, prove that x² - y² = a² - b².

If x = h + a cos θ and y = k + a sin θ, prove that (x - h)² + (y - k)² = a².

(sec² θ - 1)(1 - cosec² θ) is equal to

1. -1

2. 1

3. 0

4. 2