Question

The value of tan 10° tan 15° tan 75° tan 80° is 

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Answer 1

Here we have to find: ` tan 10° tan 15° tan75° tan 80° ` 

Now 

`tan 10° tan 15° tan75° tan 80° ` 

=`tan (90°-80°) tan (90°-75°) tan 80° `  

= `cot 80° cot 75° tan 75° tan 80°` 

=`(cot 80° tan 80°)(cot 75° tan 75°)` 

=`1xx1`          `   [ "since" cot θ  tanθ =1]` 

=` 1`