Question

tan 10° tan 15° tan 75° tan 80° = ?

Options

• `sqrt(3)`

• 1

• `1/sqrt(3)`

• –1

Answer 1

1

Explanation:

Given expression = (tan 10° tan 80°)(tan 15° tan 75°)

= {tan 10° tan (90° – 10°)} × {tan 15° tan (90° – 15°)}

= (tan 10° cot 10°) (tan 15° cot 15°)

= 1 × 1

= 1