Question

tan 20° tan 40° tan 80°= tan 60°​

Answer 1

Apply the formula
Tan A *Tan 60-A*Tan60+A=Tan3A



Hope it helps

Answer 2

Answer:

tan20.tan40.tan60

we can write a

cot(90-20).cot(90-40).tan60

cot70.cot60.tan60

cot(45+30).cot60.tan60

formula

{(cot45.cot30 - 1/cot 45 + cot 30 = cot (45+30)}

now

cot45.cot30 - 1/cot 45 + cot 30 .cot60.tan60

put values

1.√3-1/1+√3×1

√3-1/1+√3

2/1+3+ 2√3

tan60

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