Question

The value of tan 20 × tan 40 × tan 80 is

(a) tan 30

(b) tan 60

(c) 2 tan 30

(d) 2 tan 60​

Answer 1

Answer:

Step-by-step explanation:

tan10∘tan20∘tan30∘tan40∘tan50∘tan60∘tan70∘tan80∘

=tan(90−80)∘tan(90−70)∘tan(90−60)∘tan(90−50)∘tan50∘tan60∘tan70∘tan80∘

=tan80∘×cot80∘×tan70∘×cot70∘×tan60∘×cot60∘×tan50∘×cot50∘=1