Answer:
tan20.tan35.tan45.tan55.tan70 =1
Step-by-step explanation:
tan20.tan35.tan45.tan55.tan70
=tan(90-70) . tan(90-55) . tan45 .tan55. tan70
[we know, tan(90-θ)=cotθ]
=cot70 . cot55 . tan45 .tan55. tan70
= { tan70°.cot70°} {tan55°.cot55°}.tan45°
=1 . 1 . 1 [we know, tan∅.cot∅ = 1 & tan45°=1]
=1
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