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प्रश्न
The value of tan 10° tan 15° tan 75° tan 80° is
विकल्प
−1
0
1
None of these
उत्तर
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`
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