1.

tan 5° tan 25° tan 30° tan 65° tan 85° = ?(a) √3(b) 1√3(c) 1(d) none of these

Answer»

Correct answer = (b) 1/√3

We have

tan 5° tan 25° tan 30° tan 65° tan 85°

= tan 5° tan 25° tan 30° tan(90° − 25°) tan(90° − 5°) 

= tan 5° tan 25° × 1/√3 × cot 25° cot 5° [∵ tan(90° − θ) = cot θ and tan 30° = 1/√3 ] 

= 1/√3



Discussion

No Comment Found