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The value of cot 10°. cot 20°. cot 60°. cot 70°. cot 80° is :
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- 1
- –1
- √3
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1 √3
Correct Option: D
Expression = cot10°.cot20°.cot60°.cot70°.cot80° = (cot10°.cot80°) (cot20°. cot70°).cot60°
| = {cot10°.cot (90°–10°)} {cot20°.cot(90° – 20°)}. | = (cot10°.tan10°)(cot20°.tan20°). | ||
| √3 | √3 |
| = 1.1 | = | ||
| √3 | √3 |
[∵ cot (90° – θ) = tanθ; tanθ.cotθ = 1]
