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Evaluate each of the following: cot 12^0...

Evaluate each of the following: `cot 12^0cot 38^0cot52^0cot60^0cot78^0` `tan5^0tan25^0tan30^0tan65^0tan85^0`

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`(i)cot 12^0cot 38^0cot52^0cot60^0cot78^0`
`=cot(12)^0 cot(38)^0 cot(52)^0 cot(60)^0 cot(78)^0`
`= (cot(12)^0xx cot(78)^0)(cot(38)^0 cot(52)^0) cot(60)^0 `
`=[cot(12)^0xxcot((90)^0 - (12)^0)][cot(38)^0xxcot((90)^0 - (38)^0) cot(60)^0 `
`= cot(12)^0xxtan(12)^0xx cot(38)^0 tan(38)^0xx cot(60)^0 `
`= 1 xx 1xx cot(60)^0 `
`= 1/2`
...
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