Prove that :(tan69^@+tan 66^@)/(1-tan 69...

Prove that `:(tan69^@+tan 66^@)/(1-tan 69^@tan66^@)=-1`

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`(tan 69^o + tan 66^o)/(1 – tan 69^o tan 66^o) `
As we know that, `tan (A + B) = (tan A + tan B)/(1 – tan A tan B) `
Here, `A = 69^o and B = 66^o`
Therefore, `(tan 69^o + tan 66^o)/(1 – tan 69^o tan 66^o)`
`= tan (69 + 66)^o `
...

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