Question

tan69plus tan66plus 1 equalto tan69.tan 66

Answer 1

Heya
we know that
Tan(A+B) = TanA + TanB
-------------------
1 -TanATanB

use it here
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Tan(69+66) =Tan69+tan66
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1- Tan69Tan66

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so now Tan( 135) = tan ( 90+ 45)
=> - cot(45) =>. -1. -------use it here.

-1 = Tan69 + Tan66 / 1- Tan66 69
cross multiply and then we will get

tan66tan69 - 1 = Tan66 + Tan69
=>. tan69 + Tan66 + 1 = Tan66 Tan69
Hence proved .
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